I had emailed about a week ago about that also. Never heard from Adam. I just assume he doesnt have the money to pay the extra hosting fees or is just too busy to deal with it.
It also depends on the type of forum platform used as well as hosting and other limits.
I run a few different forums(some active, some new) and vbulletin is very good(the best I think) but not free. I recently setup a new forum using the "MyBB" free platform and it seems very robust and expandable for a free option. Maybe the admin can look into migrating this forum across to something like that as its only going to grow as it gets more users etc
If I put the URL from any of the photos I have on flicker between the Img brackets the photo does not show,just this;
The only way to view the photo is to right click and select Open image in new tab.
It seems more direct to just post the URL without the Img brackets and click on that.
An other forum I frequent has recently undergone renovation and now has a link under the reply box,Add Image To Post,and that links to Image Shack.This way people can post full sized images without it taking up so much of the forums bandwidth as the photos are hosted elsewhere,works well.
I use Photobucket for mine and would recomend it to all. A little more hassle granted but it means you can have an album of Phantom photos everywhere you go. Think that is still working... test:
I can only imagine how fast a big hosting package would get filled via the attachment route so Adam is likely to disable them fully (i know i would). Most of the car forums I belong to only allow linked pics.