Possible Virus Downloaded
My brother always emails videos to me that I must download. Since downloading a couple new ones from him, my cursor jumps around while using Gmail and moves from left to right and then stops in the Google search bar. This is also happens in the URL address bar. Should I be concerned? If there a safer way to view videos that he sends through Gmail other than downloading them? I never "save to disc." I never download anything attached to emails from people I don't know.
Thank you.
iMac, 10.12