A little preface:

I was previously deeply involved with skyrim modding and worked on some well known community projects such as BOSS, LOOT and the unofficial skyrim patches. I haven't yet watched the video, but have done a little research into the topic already.

Asking for payment has always been a hot topic in the TES modding community and Bethesda (until now) have explicitly stated that they are against it and have previously struck down on people attempting to sell mod content.

My thoughts:

1. The cut taken by valve/bethesda is ridiculous and modders should not agreeing to those rates. That's exactly how you devalue your worth which is a problem that already plagues the entertainment industry.
2. I don't think mod content being monetized is beneficial to the game or the mod creators in question (in the long run). A large amount of people will buy games like skyrim specifically in order to play with mod content knowing that it offers seemingly unlimited expansion to their entertainment. When you throw additional costs on top of that, suddenly it doesn't seem so unlimited anymore and the appeal is dramatically reduced.
3. Mods are inherently modular and I can already imagine the clusterfuck that's going to create regarding mods that build upon other mods and interact together now that there's money involved. Only serves to reduce the content inspired by other content.
4. Honestly, I think the majority of modders in the TES community are there because of a passion for the series and probably don't have an interest in locking their work behind a paywall. It reduces exposure and could easily stifle a mod that would otherwise be a great success. Introducing monetization of this fashion just seems like a surefire way to segregate the community to me.