I don't know if this was posted already, but I stumbled across a post on a forum yesterday and found it worked for me.
Quite a few of us used Photobucket to post photos all over the Internet on our favorite forums...and when they converted over to being a pay service, we got that dreaded box below demanding $399 a year to continue using their service.
In a previous post, it stated that there are a few browser extensions that reverse this issue and allow the pictures to be viewed again.
If you're using Google Chrome like I do, go to the three dots on the right side of the screen and click them. A drop down should appear. Hover your mouse over "More Tools," and when the next drop down appears, slide over and click on "Extensions". Go to the link towards the bottom that says "Get more extensions." In the search box, type "Photobucket Fix," and hit Enter. Three versions of this service appear...I chose the first one. Click the install button and once it's done, you should be able to see Photobucket pictures again on the forums where you saw the dreaded box.
For FireFox users, click on the three bars on the right side of the screen, then click on "Add Ons". Click search for "Photobucket hotlink" and click Install. Same result.
Hope this helps...