WikiVidi was made possible by a slight hack in the Google realtime TTS. It is inefficient and a burden to Google. I have realized this is a sinful, expensive endevour to them. I would like to forward you to the WikiVidi channel where there are plenty of videos about various topics a lot of which also use the nicer sounding Amazon Polly TTS.
This trick is:
<meta name="referrer" content="never">
<meta name="referrer" content="no-referrer">

And use the Google TTS as with the usual url.

My sincere apologies for the inconvenience.