I had been wondering who made the avi of Andrey's run, but I thought I'd elaborate more on the demo, in case you are not aware.
The demo is built much like the runs on this site, using slowdown and such to create more perfect times, rather than a pure skill run. Andrey doesn't specifically say that the demo is tool-assisted (TAS) but rather says he "made slight modifications to the source code for a more comfortable record." In case this created any confusion, there you go.
The place to go to for actual udoom/doom2/fdoom world records is the Compet-N at
http://www.doom2.net/compet-n/index.cgi . You can find demos for all different kinds of playing styles, even Nightmare movie runs. The current doom2 UV speed movie record is 26:09 right now (quite a difference between that and the cheated time :), and it will be included in the next site update which should occur on Easter weekend, so be on the lookout for it. :)