Here are some online lectures that I really liked following.

Clear, comprensive, intuitive


Title: Quantum Mechanics I (graduate course)
Instructor: Dr. Altuğ Özpineci
Link: See the course content in his website


Title: Principles of Evolution, Ecology and Behavior
Instructor: Dr. Stephen C. Stearns
Link: See the course content on oyc.yale.edu


Title: Principles of Microeconomics
Instructor: Dr. Jonathan Gruber
Link: See the course content on ocw.mit.edu


Title: Perturbation Theory and Asymtotic Series
Instructor: Dr. Carl Bender
Link: See the course content on pirsa.org


Title: cs50
Instructor: David J. Malan
Link: See the course content on cs50.harvard.edu


Title: Quantum Physics I
Instructor: Dr. Allan Adams
Link: See the course content on ocw.mit.edu


Title: Mechanics (undergraduate course)
Instructor: Dr. Altuğ Özpineci
Link: See the course content on his website
Other: Also see the same course given one year prior


Title: Electromagnetism (undergraduate course)
Instructor: Dr. Altuğ Özpineci
Link: See the course content on his website
Other:

Might not be the clearest lectures, but still there are lots of things one can learn


Title: Financial theory (undergraduate course)
Instructor: Dr. John Geanakoplos
Link: See the course content on oyc.yale.edu

Haven’t looked at it, but expectations are high


Title: Quantum Mechanics I (graduate course)
Instructor: Dr. Namık Kemaik Pak
Link: See the course content in ocw.metu.edu.tr


Title: Quantum Mechanics II (graduate course)
Instructor: Dr. Namık Kemaik Pak
Link: See the course content in ocw.metu.edu.tr


Title: Electromagnetic Theory (undergraduate course)
Instructor: Dr. Altuğ Özpineci
Link: See the course content in his website


Title: Electromagnetic Theory I (undergraduate course)
Instructor: Dr. Altuğ Özpineci
Link: See the course content in his website


Title: Electromagnetic Theory II (undergraduate course)
Instructor: Dr. Altuğ Özpineci
Link: See the course content in his website

Language courses & channels


Title: Memrise (an app)
Instructor: not applicable
Link: See their website


Title: French the natural way
Instructor: Alice Ayel
Link: See her youtube channel


Title: Coffee Break French/German
By: coffebreakacademy
Link: See their coffe break courses on their website


Title: Easy Languages
Description: Non-profit project aiming to help people learn languages through authentic street interviews
Link: See their joint youtube channel