Firefox does indeed seem broken in this way - it's putting the wrong data on the pasteboard for TextEdit.
In terms of converting text clippings, the best I can think of would be to find them all by searching for Kind textClipping or extension .textClipping and then drag them all into TextWrangler, which will turn them into text files. It might be better to put them in a snippet keeper like Yojimbo or DEVONthink after that.
In terms of converting text clippings, the best I can think of would be to find them all by searching for Kind textClipping or extension .textClipping and then drag them all into TextWrangler, which will turn them into text files. It might be better to put them in a snippet keeper like Yojimbo or DEVONthink after that.