Youtube message script

I'm new to iMacros and was wondering if it would be easy to setup a message bot. I want this to be targeted specific users, so something like entering a video url and then have the bot message random people who have commented on that video. Or are there other tools that might be able to do this already?

It's not hard at all, but keep in mind that youtube limits the number of messages you can send per-day, I believe it was 50 per 24h (last time I checked).