Isaac Arthur's latest video at the time of this posting is about alien languages and no mention of the fictional Klingon language. I am pretty sure that a Klingon would consider that dishonorable toward their race. Maybe Isaac Arthur has some fantastic skill using the bat'leth that he doesn't brag about?
A surprisingly small amount of the video was about radio communication a.k.a. SETI. The video was mostly about how language is a construct of societies and can be influenced by biology. I took some anthropology classes at the local community college but I didn't take a linguistic anthropology class which in hindsight might have been really interesting. At that time those classes were toward an associate degree in psychology which, long story, I ended up two semesters short of getting due to circumstances.
Realistically the electromagnetic spectrum is how aliens would communicate long distances and writing would be used to transmit information to future generations. Oneof the problems the video points out is radio or other EM communication would be compressed. Earth scientists could probably identify a signal as artificial but might have trouble determining the key to decode it.
As an amateur radio operator (callsign W3DTV) there are many methods of modulation and compression I could use. Under the law enforced by the FCC I can't use a "secret code" to obscure a transmission (Title 47, section 97.113(a)(4)) but I doubt aliens picking up my transmission with the Black Knight satellite can decode a SSTV transmission from a Kenwood VC-H1. I wonder if those aliens know that under Title 47, section 97.207(f) I can transmit "specially coded messages" that might not be known to them. Something roughly translated from CubeSat to English as "Arm laser weapon, aim and fire!". I bet those aliens would't see that coming. Probably something got lost in the translation.