Yes they do but the quality is not satisfying for those videos with lots of particles and thin lines which are in higher bit rate. so i can not even publish the videos on youtube because they don't look good enough for a presentation. I have them on vimeo and there was the same problem. fortunately the support was so kind to manually encode them. still not ace but good compromise.
i know d.tube is still in early stage and i'm patient. bandwidth will also increase besides the seeding option. looking forward!