Teachertube and Youtube are excellent sources of educational video and it is very simple to embed these videos into your blog. However, be aware that in 99% of schools Youtube will be blocked and so will any embedded video from this source. Teachertube is usually fine, though worth checking first.
If you want to use a video from Youtube in class, I suggest you register at Zamzar.com and use this to download a Youtube video to your PC. This can then be put on a memory stick and taken in to school for use in class.