It can be rented from most auto part stores. But being me, I purchased it because I see it as an investment and mine was under $40 (Powerbuilt). This tool will save you time and headaches.
I wish I found your video before I tried to tackle replacing my alternator. I couldn't get the serpentine belt back on after replacing the alternator. Tried for hours. Finally went to a mechanic and he had a serpentine tool and got the belt back on in 20 minutes. I don't know why all the videos I find on replacing an alternator (in my case, for my Toyota Corolla 2013) doesn't show using this tool. Please tag your video with Toyota, Corolla, alternator (as you did show all those in your video) and any other tags that might help people like me to find your video and avoid the pain and hassle that I experienced.