This is a single lecture from a course. If you like the material and want more context (e.g., the lectures that came before), check out the whole course: https://users.umiacs.umd.edu/~jbg/teaching/CMSC_470/ (Including homeworks and reading.)
Context free grammars lecture: https://youtu.be/xNHWhQrHeMU
IBM Model One lecture: https://youtu.be/seFL2wjOmRw
Music: https://soundcloud.com/alvin-grissom-ii/review-and-rest