What a man
![Very Happy :D](./images/smilies/icon_biggrin.gif)
I thought he did but I watched Safety Last with a documentary over the top and it was more sceptical about how much Harold did. In the documentary you mention Harold is credited with much of the work apart for the extreme longshots becuae you can't have the films most valuable star with no safety features at all. I also heard that if Harold had fell into his safety net he would probably have fallen out and to his death.
Personally I believe he did the stunt himself, it sits with how others have talked about him. I also believe that the friendly rivalry the big three had would encourage Harold and Buster to do their own stunts.