This form was created in 1989 by Li Deyin specifically for tournament play. It is a combined form that incorporates movements from the four major styles of Tai Chi: Yang, Chen, Sun, and Wu.
Here is an outstanding demonstration of the form by Gao Jiamin, one of the most celebrated tournament champions of our time. Not only is this a great demonstration of the form, it also identifies the movements with Chinese/English subtitles.
You can read more about Gao Jiamin in this interview, originally published in Kungfu Magazine in 2000, republished by the US Wushu Center in Portland, Oregon, where she sometimes teaches.
I originally learned 42 from my friend Long Feng in 2014, then again under the excellent instruction of Hu Pei Yi in 2016. For review and further instruction, I am using a 50-minute YouTube instructional video by Li Deyin, the author of the form. Gao Jiamin demonstrates each move; Li also demonstrates and elaborates on detail.
With the instructional vocabulary that I call Taijiese (much of it incorporated in this online notebook), I find I can understand most of what he says in this video, despite knowing just about zero conversational Chinese.
Here is the list of movements: 42-form [PDF].
Another very useful resource is a book by Li Deyin, available in English from Amazon, in which he details the standards for judging a performance of 42. You couldn’t learn the form from this book, but you can correct your form by referring to it in detail. He explains both important points and common mistakes.
I particularly like the chart that he offers at the start of the chapter on 42, in which for each move he gives the hand shape, footwork, techniques, and most interestingly, the style (school) from which the movement is derived.
Most recently (fall 2022), I have found that Qiu HuiFang offers an excellent series of four teaching videos on 42, each almost an hour long. In the first video, at about the two-minute mark, she offers a beautiful demonstration of the whole form. Instruction begins at about 9:00. Here are the links: