I'm all for dubbing aliens and Jar-Jars in the prequels, but I really don't think that alien languages is the answer. Cause alien languages mean subtitles. And subtitles mean bunch of jibberish that puts you out of the film.

I mean, seriously, Jor-El spoke English on Krypton and no one complained. Odin and Thor both spoke English in Asgard and no one complained...

Besides, those prequel movies are already cold, inhuman, fake and unrelatable-looking - so, why add an unintelligible language and alienate, say, Nemodians even more?

MagnoliaFan did an outstanding job dubbing Jar-Jar (in that YouTube video). And, personally, I think that's the way to go.