The Youtube says:

Pick a magazine and write to them. Give anything that’s relevant – what consoles you have (computer, PS3, Wii, whatever), any writing or magazine experience you have… Ask if they are looking for any teenage reviewers – mention how teenagers are the target audience for most video games! Offer to send one or two sample reviews of games you already own so they can see your style of writing and analysing games. Wait for a reply from the magazine before writing to another – that way you won’t have the awkward problem of being accepted to two different magazines and having to turn one down.