I haven't watched a movie on YouTube for quite a while because although the one and only one I watched was a regular length film, I had to watch "Part 1" and then "Part 2" etc. Is that still the case or will one click on the video show the whole film?
Yes Youtube has the whole movie with one click, no more part1, 2, etc. That was an issue with video length limits which has been changed.
It used to be video could only be 15 min in length. They dropped that restriction a few years ago. You may still find some that were uploaded that way, but now you can get a full length movie with no breaks.