@sticky_natto 1) 1 and 2 are good! 3 could also be I found a good video on YouTube for stretching I just talked to an a American person for the first time in 5 years it's very interesting to consider who the criminal is in a drama.
the first one I would change to I talked to an American for the first time in five years. the second one sounds pretty good. The third one would probably make more sense if you said I found a good stretching video because I assume you mean an exercise video with stretching exercises.
1. Close to perfect! You don't need the extra "the" before "5 years". "I talked to an American for the first time in 5 years." 2. A little bit unnatural, try: "It is very interesting to try and guess who the criminal is in dramas" 3. "stretching" would be preferred to "stretch" but it is almost perfect! "I found a good stretching video on YouTube"