Thank you for the detailed response.

I have rebooted the device (had not done so since day 1 and after installing tens of apps thought it was best). Most of the issues I mentioned above i have not been able to reproduce. I did not want to leave a review on the Nokia Store as I agree with most of what you have said above, some issues around speed are from youtube end and the others could be my device.

I am using the app now and the downloads are must faster. Happy with this. The App however has started to crash again. I downloaded a video and it worked but the video will not play or appear in in the archive or video gallery. This might have caused the crash as I tried to open it from the Transfer UI several times.
The URL to the video is
http://www.youtube.com/watch?v=vhNNkZ9YK8M

Another exception I find is that some videos download and play partially. When trying to skip ahead using the progress bar I get this message:
"cannot play video because its in the wrong format"

Hopefully the updated version you have submitted solves these issues.

Btw great app on the whole.