Would it make sense to start out with links to files hosted in various cloud storage places (google drive, dropbox or any others that aren’t going to charge by the download)? The links could be on a page within the existing ros wiki. answers.ros.org could have requests for bags from particular sensors or robots, or conversations here on discourse could drive new uploads.
If an organization with money later wants to make sure those links don’t go dead then all the files could be moved to a centralized location (maybe still google drive or dropbox, but all in one account). Licensing of the files would ideally already be in place so they could be freely copied without issue.
I don’t know if that grows into MARV integration very well though, which sounds like it would be a substantial increase in IT maintenance and hosting fees since it wouldn’t leverage the free/low-cost but more constrained hosting services.
It would be great if every visual sensor could also have a link to a video (e.g. on youtube, though again issues with links going dead later if someone takes their youtube page down) that shows off the entirety of what is in the bag so it can be quickly previewed without downloading gigabytes and incurring bandwidth costs.