In the release last month, we fixed video uploads so that webinars/screencasts get encoded with a higher resolution. This is especially useful when they show code snippets or IDEs.
However, what we also needed to do is go back and re-encode all the existing videos with this new HD profile, which is something we completed yesterday.
You should now find that any screencasts show a HD indicator & a quality selector like this;
Here are a few examples;