Importing using syntax: user:YouTube_username

Hello! As the description/details that you have it on the question sign(?) on Keyword Search for YouTube to posts, you explaining the way how to import videos from specific channel using YouTube username by using user:YouTube_username (example: user:CodeRevolutionTV). I've tried it using the username with @ and without it.. NOT working at all.. always getting the red X error sign showing up beside the select an action for running the rule. can you PLEASE take a look at it.. or if there'm more info needed, just provide it here.. THANKS IN ADVANCED!