Trend Micro Internet Security only blocks websites that are categorized as malicious by our website filtering engine. YouTube is definitely not blocked by us unless it has been added to the Exception List. For more info on how to manage the Exception List, please see: “Configuring the Exception List of Trend Micro Security software”
For other websites that has been blocked by Trend Micro Internet Security, you can double check the website's safety status using the Trend Micro Site Safety Center portal.
Please let us know if your issues persist, and we'll help you out soon. Thank you!