Regarding your screen shot post, it looks as though you've done everything right except the last step. Log onto Flickr, select your photo, select all sizes (atop the photo), then scroll down below the image and you'll see two options. Highlight the second one (URL) and paste that into the "insert image" pop-up. Try it! This one always works for me.
I posted on the thread, but don't know if you're going back any time soon.