Khan academy is multi-million pound organisation with 22 employees. If he really felt the need... Since videos are popular I don't think it matters much Maybe

Khan academy is multi-million pound organisation with 22 employees. If he really felt the need... Since videos are popular I don't think it matters much Maybe try the HD versions? You don't want it being passively presented by some clean talking newsreader. The main appeal is the conversational style of his talking.