This video deals with Nyquist Rate & Nyquist Interval
Sampling Theorem : Proof Part I- Representation
CTS using its Samples
https://www.youtube.com/watch?v=d7hPMBTaST0&t=151s
Sampling Theorem : Proof Part II- Reconstruction CTS using its Samples
https://www.youtube.com/watch?v=8MtRRtnnKz4&t=153s
Sampling Theorem : Effects of Under Sampling || Aliasing
https://www.youtube.com/watch?v=XWoyW_AFFzQ