I downloaded a video which can only be played on computers and mac to my lenovo laptop. Is there any way I can convert & watch on my laptop?

Keep in mind a laptop is also a computer & of course Macs are also computers, so I don't see how it could only play on a Mac.

Would probably help if you stated what file format it is.

You probably just need a video player that supports the format that the video is in.

On Windows VLC Media Player plays pretty much everything, maybe you should give that a try?

Install VLC player (search for it in Google.) It will let you play back just about any video format.