I recently upgraded my Internet connection speed. In effect, I can now watch YouTube HD (720p) without the pausing/spluttering which I used to have. I also had a chance to look at the Presets in Adobe's CS6 Encoder.
In the past, I have tended to upload clips with 'Target 6Mbps and Max 10Mbps'; and then let YouTube do all the necessary conversions. But, Adobe's preset for YouTube 720p HD is 'target 5Mbps, max 5Mbps'). YT don't appear to offer any guidance on the data rate; but if they cap 720p at 5Mbps; it would explain why I used to get delays on my old Internet connection (I had a max of 8Mbps which in reality tended to give a max between 4 and 6 Mbps).
Does anyone tend to set their max Mbps when encoding clips for YouTube? Is it likely that uploading a clip already encoded at the best data rate will give a better result?