Depends on how much time I have and the mood I am in. Although normally if I have the time to watch a good 30-60min that I am interested in the topic of, then I would normally watch it then and save the shorter one for later. Hope that makes sense.
For me it would depend on what they're about Like say, i'd watch a 1-5min vid of a college/uni animation project compared to a 30-60min lecture of stuff I don't care about, even if it was the most interesting lecture out there.. Or i'd watch a 30-60min game let's play over a 1-5min video or the cutest puppies and kittens
That's what I thought when I finished writing this question XD Some kinds of videos are better longer than shorter. I would edit to be more specific but ah, I'll let people interpret the question the way they want >v<