Q: Does Macbook really needs adobe flash player download in order to watch video clips on the web?

Hello Angel8C,

Your MacBook Air running Yosemite will need an updated version of the Flash Player plugin to play web content that is in the Flash format (not all video content is Flash; there is also HTML5 video, amongst others). If you are being prompted to update your Flash Player plugin, you may find the following article helpful:

Adobe Flash Player updates available for OS X on March 20, 2015 - Apple Support

Sincerely,

- Brenden