Bandwidth means how much data has been transferred. Photobucket allows free accounts to only have a certain amount of data to be transferred until it just starts showing that generic image. The data is whichever pictures you have showing all over the internet from your photobucket.

So for example, if photobucket allowed up to 10 megabytes of data transfer (bandwidth), and you had 2 pictures linked on your myspace page, and each picture is 5 MB's in size, once someone loads your page one time, you've just used up your bandwidth, and the next time someone loads your page, they'll get the generic image. If you only have one pic at 5MB's on your myspace page, someone can load the page twice (to show the image twice), and then they'll get the generic image.

I'm not sure offhand how much Photobucket's max bandwidth allowance is. Alot more than 10 MB's, but still not all that much I think. I'd have to look it up.

You can always sign up to a second/third/fourth/etc. Photobucket account if you want more free bandwidth.