Videos on most sites make use of progressive downloading, which means that the video is downloaded to my computer, and easy to trace. There are lots of extensions out there
Update:
Stream Video Dowloader Chrome extension allows to download m3u8 streams seamlessly. Install and press play on video it will identify the stream.
Addition to @aalhanane and @Micheal Espinola Jr
As m3u8x is only available for windows. Once you have identified the m3u8 url you can also use Jdownloader2 or VLC Media Player to download and concatenate the stream.
Jdownloader2: Just copy the m3u8 url when it the Jdownloader is open. It will recognize the stream in Linkgrabber tab.
VLC 3:
Open Network -> Paste m3u8 url -> Checkmark Streamoutput -> Select Settings. Choose output file, container , video and audio encoding. (e.g output.mp4, container: mpeg4, video: h264, audio: mp4a) Start Stream. It will not play the video, but encode it, showing the encoding progress by moving the video play back progress bar.