In November 2021 Channel 9 became part of Microsoft Learn, and the site videos were embedded from closed.
However, Channel 9 videos are still available via the Internet Archive, so can be embedded as HTML5 videos. There is a Channel 9 Index 
which will help find the video's page in the web archive. You might have to inspect the page source to find the link that can be embedded.
Find pages with Channel 9 videos.
ITEM video TEXT CHANNEL9
The Channel 9 Index provides links into the Internet Archive Wayback Machine's archive of the old Channel 9 MSDN site. This appears to contain pages in a mix of different languages. But, below the video there are three tabs - Description, Embed, and Download. Use the Download tab to find the link you need for embedding a HTML5 video item.
As an example, a video of the late Bill Hill talking "There is only one space after a period" . Double click the caption in to see the plugin markup.
HTML5 mp4 https://web.archive.org/web/20211022041353/https://sec.ch9.ms/ch9/e554/78e3c1d0-8953-43cd-af48-dc0fb173e554/BillHill2004OneSpace_high.mp4 Are you a one spacer or a two spacer? Bill Hill gives his opinion on why you only put one space after a period. This video was shot in 2004.