For these CCC videos, please link to media.ccc.de. They built a media distribution platform for us that gives higher quality, allows downloads, and uses no tracking. Why not use it?
https://media.ccc.de/v/32c3-7435-replication_prohibited#vide...
https://media.ccc.de/v/32c3-7435-replication_prohibited#vide...
Sounds like what happens to me when opening the page. Did you try to click on 'Video' tab or on the 'Play' button? It started the video for me.
Trying to play http://ftp.halifax.rwth-aachen.de/ccc/congress/2015/h264-hd-... directly in the browser works.
Maybe they should just load that in an iframe or something.
Mixed Content: The page at 'https://media.ccc.de/v/32c3-7435-replication_prohibited#video' was loaded over HTTPS, but requested an insecure video 'http://ftp.halifax.rwth-aachen.de/ccc/congress/2015/h264-hd-web/32c3-7435-en-Replication_Prohibited.mp4'. This content should also be served over HTTPS.
FWIW Firefox plays it just fine