Hopefully you have a song recorded all ready. It doesn't have to be pro quality. Home recordings on consumer grade machines sound pretty good these days. You can synch up the audio recording to the video footage.
Now consider what you want to happen in your video. Will it have scenes of you and your band mates playing your instruments and singing or will it be more creative and tell a story? Personally my favorite videos have at least one attractive woman in them so this is something you might try and make happen. You might also try and find a sponsor for your video so you can get some money or free stuff. I am going to write an article about this in the future.
Once your video is shot and edited you will want to upload it to the internet. Something I have done in the past is to submit my videos to Blank TV. They will put your video on their youtube channel with over 300,000 subscribers and you can many views this way. A video I shot for The Jerkwadz got over 1,900 views on Blank TV and I was pretty happy with that.
So if you don't have video yet just go out and make one! It's a lot of fun and will get you more exposure and could possibly lead to opportunities.