> w/ww.youtube.com/user/examplechannel
> The links to the extra comment pages are as
> follows.
> w/ww.youtube.com/user/&start=10
> w/ww.youtube.com/user/&start=20
> w/ww.youtube.com/user/&start=30
> 
> +*&start=* doesn't do anything.  
> Maximum mirroring depth is 1.  Any more and the
> backup will go on too long.
The main page is depth 1, the first comment is depth 2, the continuation is 3,
etc. Don't use depth. 
What else is below /user that you don't want? Filter that out. Worse case
filter:
-* +*/user/* +*start=* +*.js +*.css

> It just archives a blank page for comments.
> These comment pages seem to be dependent on what
> youtube channel is currently viewed.  I think they
> may use javascript.
The default is to go down only. Any JS/CSS files are not likely below /user.
Use the near flag (get non-html files related) to get everything required for
the page

Next time don't tell us what you think you did, give the actual command (log
file line 2 or doit.log)