Carl Bender's lectures on very powerful but non-rigorous perturbation theory methods used in theoretical physics:

[Part 1][1]

[Part 2][2]

[Part 3][3]

[Part 4][4]

[Part 5][5]

[Part 6][6]

[Part 7][7]

[Part 8][8]

[Part 9][9]

[Part 10][10]

[Part 11][11]

[Part 12][12]

[Part 13][13]

[Part 14][14]

[Part 15][15]


  [1]: https://www.youtube.com/watch?v=LYNOGk3ZjFM
  [2]: https://www.youtube.com/watch?v=tV-xIhP7VU8
  [3]: https://www.youtube.com/watch?v=_Sm7SNlNUOI
  [4]: https://www.youtube.com/watch?v=VvqeJkT3uyo
  [5]: https://www.youtube.com/watch?v=LMw0NZDM5B4
  [6]: https://www.youtube.com/watch?v=nWKYrpKn3-0
  [7]: https://www.youtube.com/watch?v=pyEQXMKfEnA
  [8]: https://www.youtube.com/watch?v=YGDTW7mNUKM
  [9]: https://www.youtube.com/watch?v=rs2iJugn808
  [10]: https://www.youtube.com/watch?v=vem9Ltth_Hg
  [11]: https://www.youtube.com/watch?v=9OO-gqj3N0c
  [12]: https://www.youtube.com/watch?v=clpHq5Rs8a4
  [13]: https://www.youtube.com/watch?v=ibR4k-HvRm4
  [14]: https://www.youtube.com/watch?v=31TegmZpIyc
  [15]: https://www.youtube.com/watch?v=RqZ0VsEc4F0