The #hyperdeck is a bit picky, but looks like the #h264 level is the main issue, set it to "main" then it happily plays videos.
And obviously the video resolution and fps needs to match with the current settings.

Annoying issues with #hyperdeck recordings, audio is 3 frames early. Can't figure out why. #blackmagic #blackmagicdesign

One more thing I'd like to tinker with but don't need, a #hyperdeck
#blackmagic