I expect that the performance issues with small assets are probably minor (and smart phones have hardware acceleration for it). H.264 is expensive to encode, bu

I expect that the performance issues with small assets are probably minor (and smart phones have hardware acceleration for it). H.264 is expensive to encode, but the decoding cost is much lower, and is also adjustable at the cost of the compression ratio. If you want transparency, then the workaround you currently have to do with going through an off-screen canvas is another story for performance. I can think of one other hypothetical problem, although it would need testing to confirm: block sizes. h.264 works with block sizes that are a multiple of 4, and AFAIK codecs often perform sub-optimally with input that cuts off mid-block. For large videos that doesn't matter much, since you don't usually focus on the edge of a video, but for a small asset, it might be a problem. Someone with more knowledge of h.264 might be able to correct me on this.