Should I be worried? Please help.

My 8 month old nephew is starting to exhibit some strange signs. He lifts his hands hands up and constantly moves his wrists around. He first started doing this a few months ago but it is happening more and more. If he is sitting in his walker or on the carpet, he just always puts his arms up and moves his wrists all around. It looks as if he is revving up a motorcycle or something. He also has been having episodes where his eyes roll back into his head for a few seconds and then he snaps out of it. His arms are usually up when this happens and it does not look normal. The last time this happened, you could not see his pupils so I do not think he is simply looking at the ceiling. Lately, he has also started with some head shaking. All of a sudden he will shake his head from side to side and you cannot tell if it is because he has just learned to do this or if he cannot control it. I realize some of thses symptoms can be nornmal, but seeing them all happening at the same time makes me worry. My brother and sister-in-law do not seem to think it is anything serious and that it is normal. You can tell they really do not want me talking about it but I am worried. I do tend to overreact but I don't want to ignore a feeling that something is wrong and I didn't do anything about it. I have been looking online and found this site. I read an old message from last year on this board and thought maybe one of the current posters could shed some light on what is going on. Since this is not my child, I cannot just call the doctor and make an appointment. His parents do not seem to think it is necessary to take him to the doctor as they think this is just normal baby behavior. Also, I want to mention that my nephew has always loved movement from the second he was born. And not just movement but heavy bouncing. I don't know if that could be connected or anything, but he seems to only be happy when he is bouncing. He is not crawling yet either. When he was younger (in the first few months) he always had his head cocked to one side and I read that could be a sign of epilepsy. Otherwise, he seems perfectly happy and healthy. Should I be worried or am I just being over-protective? Any advice would be GREATLY appreciated.