What ??? How ? Our content is only text and images (videos are usually GIFs or external links)... Although I noticed recently that one can upload videos...
Have you considered cleaning too old or irrelevant content ? (don't know if that would trim any costs in hosting)
I'm no forum expert but I thought any updates involved only the front/backend of the server mostly how things look and how things communicate with the server which I thought would be relatively small like 300MB or something ...
Took a look at InvisionCommunity, they don't seem to share what kind of CMS they use like Wordpress or Joomla so I guess they use their own or a weird mix of common ones...
Dayum ! and people were complaining about Maxon's prices ...