1. I thought of other names but I was not satisfied with any of them.
2. I thought of other names but I was satisfied with none of them.
(Are both the same?)
4. I always watched him "working" when I was young.
(Did "I" watched him working for some time?)
5. I always watched him "work" when I was young.
(Did "I" watche him work for the whole time?)
1 and 2 mean the same, yes.
4 and 5 both mean that "I" watched him work over a period of time WHEN "I" WAS YOUNG. The "always" is a little vague. I always watched him when I was with him, or I was with him all the time (the whole time) he worked. The sentences do not specify which.