There are actually a number of short Youtube videos showing T-cells attacking cancer cells, and perhaps the one below is the one you reference.
But even if it's another one, they're all showing the "good guys" on the attack, taking it to the malignant intruders.
This kind of video brings to mind one of the challenges that researchers face, namely making such attacks possible, by figuring out how to get around the often clever strategies that cancer cells have been known to employ, to distract, confuse, or fool bodily defensive mechanisms into leaving them alone.
But when those bodily defensive mechanisms DO find and recognize them, the result is videos like the one below!
GO T-CELLS!
But you're right, there is something satisfying in seeing the cavalry coming to the rescue!
https://www.bing.com/videos/riverview/relatedvideo?q=%e2%80%9c+t+cell+destroying+cancer+cell%e2%80%9d&mid=b04dd5bc9d065853ab68b04dd5bc9d065853ab68