No Videos Available for speedups

Is there a reason that videos are only rarely available for non-training speedups, such as exploration, amber trading, resting defender dragons, and so on? Oddly, this also seems platform dependent - on my phone videos are somewhat more likely to be available for these speedups, while on Chrome OS they are almost never available. Does anyone else have a problem with the game exiting after watching a video to speed up resting a dragon after ‘Defending Berk.’