It won't be considered plagiarism as we are not selling the full copyright of our videos. We are only licensing you to use them without any modification in the videos. You will receive videos with your company logo.
So you sell the same video to three different companies, the only change is branding by adding a logo, right?
Honestly, it looks pretty much like plagiarism to me. Honestly, the idea is good, but I'm not sure how many companies will find it attractive if everyone in the industry has the same tutorials.