I read that section before posting, and I understand what it means.
The "Easy One Page Method" is just an embedded link to www.servimg.com, a free external image hosting service that requires a valid account to use. When WRR/X forum members upload images via the "Easy One Page Method" they're uploading them to an external server independent from the forumotion web servers. A servimg.com account is automatically created for users who join this forum, which saves a setup step and makes it easy to upload images to this particular WRR/X forum. However if you use servimg.com to host images for other forums (other forumotion or external forums like ThumperTalk or ADVrider etc.) you have to upload the images and manage them via the servimg.com user interface on their website.
More info here: http://help.forumotion.com/t10583-servimg-tutorial