Ellixim's point #2 put it perfectly. We do have some threads about other games (though not many - those forums were way more active before the release of D3, when DFans had a very different user base); but posting in this subforum does not mean one can ignore our general rules, such as regarding video posts.
One thing I'd like to add is that our forum rules are not something we as moderators came up with to impose guidelines on the community. Rather, I'd like to see the rules as generalized, abstract guidelines that we derived from the wishes expressed by our community (especially the video section in our rules is based on requests by many regular DFans members). Our job as moderators is to consider those rules as guidance to mediate when necessary. As for your posts, the community's feedback was unanimous that the video rules' violation outweighed the community's benefit (regarding the potential discussion of other games).