Hi K. -
It could be teething, and if it is, you may want to offer your son comfort by rubbing some Baby Orajel on his gums and giving him a cold teething toy to chew on when you lay him down for a nap.
You mentioned that your son watches TV...he could be too over-stimulated to take a nap. When my son was this age, I noticed that if he was over-stimulated either by the TV or his surroundings (too many visitors or too much noise), he'd have a hard time settling down for a nap. I'd try cutting down on the TV time and maybe letting him play in a super saucer or with some other interactive toys. Super saucers are great for building leg strength, by the way. I'm convinced that both my children started walking between 9 - 10 months because they spent time in their super saucers.
Regarding nap times, what eventually worked for both my kids was to feed them, put them in their super saucers for some play time, give them warm baths, and then put on their lullaby CD. It got to the point where as soon as I started up that CD, they would nod off in no time and nap for a couple hours straight. To this day, both kids konk out to the lullaby CD, and I have to confess, so do I. Everyday, we sleep for a couple of hours after lunch...in my culture, we value siesta time VERY much.
Take heart, as babies get older, their little bodies will put out so much energy because they're growing at such a fast rate that they simply can't help but take naps. During this time, you'll have to manage not letting your son sleep TOO long. Imagine that! :)
Keep us posted. Blessings to you and yours.