I have found Youtube to be helpful many times. There is a wealth of video resources explaining many, many topics. However, it is important to preview all videos before using them, for appropriate content and advertising.
It is a great source to find video clips to help kids understand books that are read in school or to show kids correct form in athletics. Kids are in love with video so they seem to be very interested when showing anything via this format.
I use youtube for various reasons, both professionally and personally. Visual Phonics is a great tool for teaching kiddos letter sounds and we start our mornings with a youtube video by Jack Hartman that is a wonderful Visual Phonics supplement and grabs the preschoolers' attention.
I use YouTube a lot, too. We like to watch informational videos during nap time on subjects we are learning about. I always try to put "for kids" behind the topic search and that helps. Although, sometimes, I get adult advertisements. The worst is for scary movies or gifs of girls shaking their assets.