IIRC, you would upload wav or mp3 to YTMND, and then it would play back in Flash. I think it worked like this for one or both of these reasons: 1. Syncing the

IIRC, you would upload wav or mp3 to YTMND, and then it would play back in Flash. I think it worked like this for one or both of these reasons: 1. Syncing the audio and video. It is difficult to sync a gif with audio. They have to be started at the exact same time, be the exact same length, and never get out of sync due to lag/stutter. This wasn't important for early YTMNDs, but mattered later when people created what were disparagingly referred to as "___ short films". 2. Bandwidth. I think Max had said the Flash solution was more efficient than serving the raw audio and gif. Think of it as an early version of WebM. I think the use of Flash could be controlled on a per-YTMND basis - the creator could disable the use of Flash. And/or maybe it was that Flash was only used for animated gifs?