Varies: There is no specific dangerous heart rate during exercise. How fast your heart beats with exercise depends on a number of factors, especially your conditioning. If you are healthy, a heart reate in the 170's or even higher may be ok and tolerated.
Motion sickness caused by video games, sometimes called simulator sickness, is caused when there is a disconnect between what your eyes are seeing and what your body is feeling.
Vertigo or motion sickness: Dizziness related to motion sickness or dizziness related to problems in your inner ear that feel exactly like motion sickness are major causes of nausea. Indeed, this is probably the most treatable cause of nausea. There's a reason that nausea and nautical have the same root word.