I always recommend Jerry Miculek's "Trigger Job" video for anyone who wants to work inside S&W revolvers. The video has good close-ups of the small parts, and it gives good coverage of assembly and disassembly. It shows what areas can be smoothed, and most importantly, which areas should not be touched. Even if you don't want to touch parts with a stone, I think this video is a useful introduction to the internals of S&W revolvers.
I have also taken a look at most of the revolver trigger job videos on youtube, and I cannot recommend any of them. Some of them do have good info, but every free video I have seen also has problems. In my opinion, it is worth paying for Jerry's video.
Note, that Jerry has also made a Disassembly and Reassembly video. I have not watched it, but I can say that these areas are well covered in the Trigger Job video, so I think that one is sufficient.