Video issues, not playing

I suddenly have an issue with videos. Uploads is OK, but they will not start playing ?
If I upload the site 2-3 times some of the videos will play.
Connection to my site using a ftp client and download the videos, the videos that will not play is corrupt.
I did not have this issue before, many a bug in the latest Sparkle update ??

I’ll get in touch privately, we’ve heard one other mention of video corruption, though we’ve never seen it.