In our case - we couldn't call content plugins because they are written for com_content, not for com_jcomments and I think this isn't good idea use plugins for other component (with compatibility reasons). I mean support it in JComments core.
Yeah, I suspected something like that. Bummer!
But I think that we can make some external plugin for JComments to support this feature.
That would be really cool. Apart from being able to handle quite a list of media files, RokBox can generate thumbnails with preset dimensions from external images. Comments typically don't have much room and any image is likely to either mess up the page or be cropped which is a problem.
p.s. I notice that you site is called newrussianamerica - do you know russian?
Yes, I do. I am Russian. Born and bread.