UUF: IIS video links for CH9 removed, relink to shows/iis-net-site-videos

UUF issue:
In this iis-docs commit some of the IIS videos were given up for missing and their links removed from their intro docs.

Many of the IIS videos appear to have been moved to here to be saved when CH9 content was removed:
https://github.com/MicrosoftDocs/iis-docs/commit/a760974829f669785ac49785a6d6b9610e294311#commitcomment-153242720

However, it turns out some of those videos survived and were moved here:
https://learn.microsoft.com/en-us/shows/iis-net-site-videos/

For example:
https://learn.microsoft.com/en-us/shows/iis-net-site-videos/extending-web-server-functionality-in-net

We are still getting a number of UUF customer requests for fixing these remaining ones.

Following the commit above that removed the link, put the links and video details back in for those videos that are still available at the shows/iis-net-site-videos location.

Tracking this here since we are not taking new public issues on the iis-docs repo. Assigning myself.

Some similar ones like these were fixed in the past, see related issue: https://github.com/dotnet/AspNetCore.Docs/issues/32554