I enjoyed the webinar. No problems with the audio, I suggest that the presenter could have had a better microphone. He also could have tailored his presentation more towards X-cart simply by substituting his WordPress examples with XC. Overall though I think he did a good job covering the bases.
Just a little too much selling his services and not enough focus on XC. I think you could connect better with your audience if you presented the webinar yourself. Perhaps it could be scripted and pre-recorded using screen capture. You could hire a native english speaker to record the body of the presentation that has been scripted by your team and possibly adjusted slightly by the speaker.
After the scripted, pre-recorded section (maybe about 30-45 minutes) you go into a question and answer session. To get instant feedback from the audience and not depend upon email I highly recommend a question and answer system that allows us to enter questions directly into the chat box. These questions can then be moderated by your team, and posted on the audience screen only when the question is being answered. This helps the listeners to remember the question while they are listening to the answer.
One system that I am familiar with that features such a setup is
adobe connect.
Anyway these are just some ideas on how I think it could be improved. I think it was very successful, it looked like you had great attendance.
I'd never read the developers section before, seems like a great idea for those that are truly stuck and can't upgrade. New trick has been added to toolset. Thanks.