Right, Do you want the techy answer or just the one that says it won't work ???
The problem lies in the handling of the BBcode used in the forum. It works for .jpg, .gif, .bmp etc. but the links you've got from online.ie are what's called dynamic images.
Basically, they're not "proper" pictures. They're manipulated using php code and as such don't have a useable filename/extension for this board.
The BBCode tags on this phpBB forum sadly doesn't support dynamic images VZi is running on VBulletin which may have different features (plus it's not free so you have to spend cash).
There may well be a mod to work around it & get those types of images working but to be honest volkstorque development is about to grind to a halt cos I've barely got the time & with my new project I deffo won;t have any. Anyone wanna take over the dev ?? Mail me
Alternatively ..... They just won't work