I'll try another video shortly to test it, the last one I tried was quite big and did eventually work - it just took a couple of hours after I uploaded it before it played back correctly.
btw, i notice that you are only voting for a small number of steemit witnesses, it would be really helpful if you would add me to your list there - witness votes are weighted like normal votes are, since you have some Steem Power built up, a vote from you would make a good difference to my campaign and once I am 'voted in' I can start to help fix up Steemit to some extent - maybe eventually doing things that help services like Dtube (witness powers are somewhat limited in that regard, but they do get heard more than average users). cheers for your support here anyway! My witness application post is here.
I just voted for you as witness. I wish you luck with that and thank you for explaining what a "witness" is in your post so clearly as I barely had any idea. Now I get it.
Cheers, and keep up the good work.