I was a bit confused at what the joke was from reading the subs and had to listen to the actual audio to get what "Bakemono-ese" was supposed to be.
It turns out it was a different parsing of 化物語 . The title is a portmanteau of 化物 (bakemono) and 物語 (monogatari). However, "No, I Ain't Nessy" read it as 化物 and 語 , thus thinking it was the 語 (language) of 化物 , hence "Bakemono-ese".
Incidentally, the reading provided by "No, I Ain't Nessy" is "bakemono-go". "go" is the on'yomi reading of 語 , which is often used for languages, such as 日本語 (nihon-go) for Japanese. Meanwhile the kun'yomi reading is "kata(ri)", which is "softened" into "gatari" in 物語. The different reading used was what finally completed the joke.
