OK. I am assuming what you have posted so far is still the same. If it is not, correct the info that I am using that you have posted.
You say the same video with a HTTP request to the site is not throttled. Also you say there is actually no difference between the sending of the HTTP and HTTPS videos other then the request, both videos are sent in the clear. If you read the thread that swintec
posted you will see that CDNs include throttling info in the URLs that fulfill the request. So the likely reason is that the CDN is adding throttling info when you send a HTTPS request.