s3ph!roth
i believe game companies once made a research here and they were disapointed that trough out the Philippines, 97% of gamers are using illegal copies/pirated rather than original. They had an interview and most of them said originals are too expensive and rather buy games cheap. So now they dont show advertisements any more but they still sell games.

Vernan
I have seen video game ads on Studio 23 before. It was shown during the commercial breaks of an IT review show. The show included reviews on softwares, gadgets, and video games. The show no longer airs. Another show from Studio was Quik-E, I think it also showed video game ads, but Quik-E is no longer airing. The video game companies will most likely not advertise their products in shows other than IT shows or shows dedicated to gaming because TV commercials are based on the target audience.

Ra
In addition to what the others said about TV demographics, developing countries still deal with piracy and similar information protection issues, which is why you don't see many DVD adverts neither. Mass marketing entertainment products (besides sloppy theater movies owned by TV networks) doesn't pay-off yet for companies.