You can search YouTube videos uploaded by some user if you try the following things:
First of all open youtube.com in your browser.
If you know the exact name of youtube channel then you will type as https://www.youtube.com/basiceducation2050
You have typed "basiceducation2050" after the main website https://www.youtube.com/ assuming that the name of channel is basiceducation2050.
Similarly, suppose you want to search videos uploaded by "basiceducation2050" then you will simply type "basiceducation2050" in the search box of YouTube.com
This way, you will find many of the uploaded videos by specific user if not all the videos by that user. And when you search once your required user; most of that user's videos will be automatically listed by youtube for you to run next video of the same user.