Your package seems to clobber a bunch of mime-types into running "Netflix-style", like Netflix-Launcher.

[vaguerant]

$ cat /etc/mailcap | grep netflix
text/html; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
text/xml; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
application/xhtml+xml; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
application/xml; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
application/rss+xml; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
application/rdf+xml; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
image/gif; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
image/jpeg; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
image/png; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
x-scheme-handler/http; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
x-scheme-handler/https; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
x-scheme-handler/ftp; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
x-scheme-handler/chrome; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
video/webm; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"
application/x-xpinstall; chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com %s; test=test -n "$DISPLAY"

As you can see, all (?) web-related mime-types are being triggered via your custom Netflix user-agent and URL. This means, e.g. clicking a web link from another app results instead in opening a Chromium window (or tab if it's already running) on Netflix.com rather than what the user intended.

I'm a Linux amateur, so I'm not even sure how to go about fixing this. As-is, it kind of cripples the functionality of a web browser when clicking links is broken. Help?

EDIT: Again, I'm a Linux amateur, so I don't know what populates what, i.e. whether changes to /usr/share/applications/mimeinfo.cache are read into /etc/mailcap or what, but another apparent symptom of this can be found in the former:

$ grep netflix /usr/share/applications/mimeinfo.cache
application/rdf+xml=netflix-launcher.desktop;
application/rss+xml=netflix-launcher.desktop;
application/x-xpinstall=netflix-launcher.desktop;
application/xhtml+xml=netflix-launcher.desktop;
application/xml=netflix-launcher.desktop;
image/gif=netflix-launcher.desktop;display-im6.desktop;display-im6.q16.desktop;gpicview.desktop;
image/jpeg=netflix-launcher.desktop;display-im6.desktop;display-im6.q16.desktop;gpicview.desktop;
image/png=netflix-launcher.desktop;display-im6.desktop;display-im6.q16.desktop;gpicview.desktop;
text/html=netflix-launcher.desktop;chromium-browser.desktop;
text/xml=netflix-launcher.desktop;chromium-browser.desktop;
video/webm=netflix-launcher.desktop;
x-scheme-handler/chrome=netflix-launcher.desktop;
x-scheme-handler/ftp=netflix-launcher.desktop;
x-scheme-handler/http=netflix-launcher.desktop;chromium-browser.desktop;
x-scheme-handler/https=netflix-launcher.desktop;chromium-browser.desktop;

EDIT2: I believe that the root of the issue might be in the netflix-launcher.desktop file that you include in your package.

[Desktop Entry]
Version=1.0
Name=Netflix-Launcher
GenericName=Netflix Launcher
Comment=Launch Chromium pre-configured for Netflix
Keywords=Internet;WWW;Browser;Web;Explorer;Netflix
Exec=chromium-browser --user-agent="Mozilla/5.0 (X11; CrOS armv7l 6946.86.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.84 Safari/537.36" http://netflix.com
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=netflix-launcher
Categories=GNOME;GTK;Network;WebBrowser;
MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;x-scheme-handler/chrome;video/webm;application/x-xpinstall;
StartupNotify=true

Specifically, the MimeType line. Lay user guess: since it's installed after Chromium, it's gobbling up all these MIME-types you list here. I don't think it's really necessary for this shortcut to be handling any MIME-types at all, since its use case is to launch it directly when wishing to view Netflix.

I've now rectified this issue on my end. I removed the MimeType line from my personal netflix-launcher.desktop and ran a sudo update-mime, which corrected my mailcap. I then ran a sudo update-desktop-database, which updated my mimeinfo.cache . Everything now seems to be behaving as desired.

[BruneXX]

Hi Guys, I'm here with something strange...
Currently in raspbian, if I run chromium with normal lancher:

1. Then set the user agent switcher to netflix
2. Go to netflix and play a movie
3. I'm receiving the following error: M7121-1331 and stuck there... no way to go

BUT! .....

If I open chromium with the Netflix Launcher (and I don't know why, because is same user agent in both cases..)

1. Open with Netflix Launcher
2. Go to netflix and play a movie
3. It works like a charm...

Anyone has experienced this issue? is relatively new because this was working well past week so..

Thanks!