Ask HN: Service to modify video playback rate on mobile phones?

I am currently in the process of developing a service that would provide users the possibility to increase/decrease video and audio playback rate. I know there are a few software programs that already do this (e.g. enounce), but these are only available on the client side. The service I am developing is server side in order to be able to use it on mobile phones (do you know of any?)

I have some doubts about how useful this service can be, so if you could make some suggestions and clarify a bit, it would help me a lot.

1) Do you find this service useful to have it on a mobile phone? Or maybe you use the increased/decreased playback rate only on long videos that you usually watch at home?

2) I know HTML5 is getting better and better support and that video/audio elements have a playbackRate attribute, but I was wondering if you think this can (on the short-term at least) be implemented on mobile platforms (limitations due to CPU, battery life, etc.)

Any other suggestions or thoughts are highly appreciated :)

Thank you!