I've exceeded my bandwidth limit only once, or twice, since using photobucket, and that's been over the course of 8 years or more. I usually post updates to my build threads on two different forums, but at that time I was probably using three or four, so my photos were getting a lot more hits. Videos can consume a lot more bandwidth also, so if you are constantly going over the limit, you might want to share the videos through youtube instead, and save photobucket for the photos. Even really old photos you have posted on forums can still pick up some interest now and then, so everything you've ever shared counts against the bandwidth limit.
As far as storage goes, I came close to using up my maxed allowed limit, but then photobucket must have expanded because now I'm barely at 7% of the space limit. When I did come close to having a space problem, I just created another free photobucket account for more photos, rather then pay for an upgrade.
Now I have way more space then I need! I'm sure the photobucket staff would frown upon doing that, but none the less......