Usually thoughout the day I'll be watching many different videos and then one will stick with me. Someone will have made a really good point at like time code 3 mins and 17 seconds or something. If I have to right then and there pause the video and start a download it takes me out of the moment. I like it so much better to just at the end of the day go back and find good moments and place them in a their own videos. Examples:
https://www.youtube.com/watch?v=ksHaSnEs4WM
https://www.youtube.com/watch?v=KRfsAufKrzk
https://www.youtube.com/watch?v=6EoH-Qy_xw8