Well, first off, go and get your money back if it isn't fixed!
When you say you cannot see vids, what does that mean? Streaming on some but not all? Only local and no internet? What are you using to view them? Does that program have the appropriate CODEC to view the video? What type of format are you wishing to view? If some work and others don't , what is the difference between them?
Let us know s we can assist.