Just use forum's attachment feature please, c'mon, don't understand why still use those free external hostings ?
Because it is more convenient.
Uploading as an attachment means
1. Limited to 1M per file
2. Limited to 2M total per post
3. Can upload only one file at a time
4. Have to remember how to embed attached photos into the correct place in post instead of just as thumbnails at the bottom
5. You might want to post the image somewhere else as well, not nice (maybe not possible) to do that if they are uploaded as attachments