Here is a post that addresses your question
http://tubetoolbox.com/forums/default.aspx?g=posts&t=341In addition, the following is contained in our FAQs:
Q. Can my YouTube™ account get suspended for using Tube Toolbox?A. NO. In fact, YouTube™ specifically addresses automated software (like Tube Toolbox) in section 4.G of their Terms of Use (quoted below).
"You agree not to use or launch any automated system, including without limitation, "robots," "spiders," or "offline readers," that accesses the Website in a manner that sends more request messages to the YouTube™ servers in a given period of time than a human can reasonably produce in the same period by using a conventional on-line web browser."
Tube Toolbox has a Send Delay option which allows you to put a timed delay between each Message, Comment and Friend Request sent. This will ensure that you do not break their Terms of Use.