With the removal of XML from VideoAlpha in #455, we have separate fields for each speed, and the Youtube string is only present for backwards compatibility. The VideoAlpha module has to create this string from the individual fields. Would it make sense, then, to send the streams as a JSON dictionary? This would allow us to simplify the interface somewhat. Let me know what you think -- if we choose to do this I would make the change as a part of my PR.