When I tried to post a video and went into my library of photos and videos none of the videos came up as a choice to post only stills. I never noticed that before.
I tried loading a video without using the TF app, it did give the choice and I tried 2 times 1 short 27 sec. and the 2nd 1 minute & 23 sec. It appeared they were loading but after a considerable time waiting neither one would finish loading.