Mediaccc links support

[B0pol]

• I carefully read the contribution guidelines and agree to them.
• I checked if the issue/feature exists in the latest version.

https://media.ccc.de/v/oscal19-12-the_hairy_issue_of_end_to_end_encrypted_instant_messaging
It should open as a video. Not supported by extractor, we have "link not supported" toast.

https://media.ccc.de/b/oscal19
It should open as conference (or channel for a youtube comparison). Not supported by extractor, we have "link not supported" toast.

https://media.ccc.de/c/oc it should open as conference. It's supported by the extractor, but not by the app (try with sharing it into newpipe).