On January 27, 2015, YouTube announced that HTML5 would be the default playback method on supported browsers. YouTube used to employ Adobe Dynamic Streaming for Flash, but with the switch to HTML5 video now streams video using Dynamic Adaptive Streaming over HTTP (MPEG-DASH), an adaptive bit-rate HTTP-based streaming solution optimizing the bitrate and quality for the available network.
For example if your YouTube Channel happens to provide valuable video content for a very specific audience. Say the channel teaches business owner how to organize their finances, track their expenses and save money on taxes. Any company who is trying to reach business owners would love to place their ads on that channel because you would both share the same demographic. The people who view that channel are their potential customers.