I stress out a lot when i watch games. is there a long term effect of watching a lot of sports intensely?

Possibly: I believe many of us who partake in that activity feel as you do at times. It can be a problem if you would have uncontrolled hypertension, a heart rhythm abnormality, or anxiety disorder as these may be made worse by the adrenaline and other chemicals put out during the excitement. This is also an issue if not more so with video gaming...Regular checkups with your dr. Should pick up any problems.

Balance it.: When you stressed out- either because of watching games, or any other stress, your body reponses by producing the hormone of stress- cortisol, which if not being "washed out" by regular exercise, may lead to "wear and tear" in multiple organs, including heart, blood vessels, kidneys, etc. Therefore balance out watching games with taking care of stress hormones in your body. Exercise!