Khan Academy has great video clips with detailed explanations of every middle and high school math topic (including linear algebra and statistics!) It's great for giving some variety in INM for students and having students practice note-taking skills by watching short video clips. It's also a great place to figure out how to explain complicated math topics.
Sejin, this is one of my favs! Science teachers and social studies teachers there are also excellent short clips on chemistry, biology, physics, economics and money and banking. Sal Khan's story is worth a look. He's a Ted talk presenter, has been featured on several news programs. This resource is excellent.
This resource is especially useful for activities dealing with geography for both guided and independent practice. It also has short video clips for hooks, and great ideas for lesson plans!