MAX_VIDEO_LEN value change in RL_Trainer __init__ doesn't actually update the global value of the parameter

[bri25yu]

Not sure if this is even a relevant parameter or not, but I'm pretty sure the global value being used by:

• https://github.com/berkeleydeeprlcourse/homework_fall2022/blob/main/hw1/cs285/infrastructure/rl_trainer.py#L179
• https://github.com/berkeleydeeprlcourse/homework_fall2022/blob/main/hw1/cs285/infrastructure/rl_trainer.py#L222.