I love that you're getting all 3 instruments into these, it sounds awesome.
kdenlive (https://kdenlive.org/en/) is a free/open-source video editor that can do pretty much whatever final-cut pro can do... but is kind of awkward. Its also a linux/windows thing, so you'd need to get creative trying to run it on mac. Good luck.
Fiddle is a playing style. You may want to try an open tuning on the strings (A E A E). I also highly recommend this songbook Old Time Fiddle round peak style
For bows, if you want something cheap but still good check this one out
Fiddlerman Carbon Fiber Violin Bow 4/4 https://www.amazon.com/dp/B00K0NZQHY/ref=cm_sw_r_cp_api_i_17FTZJKCF5BXQ40GAF13?_encoding=UTF8&psc=1
I’ve got a nice $550 bow that sounds great but I usually end up playing with the one linked above and it’s totally fine and is more resistant to humidity and all that!
What type of music does he enjoy? You could consider a classic tome such as "The Dance Music of Ireland: O'Neill's 1001 https://smile.amazon.com/dp/1857200276/ref=cm_sw_r_apan_glt_fabc_WW550MNR0XNSYH00RK4K?_encoding=UTF8&psc=1"
I know you mentioned preferring to learn by ear (me too), but it's nice to have some written settings of tunes he may hear in passing but doesn't fully learn. Good luck!
A good metronome if he doesnt have one.
This great little tuner that clips on the violin Planet Waves PW-CT-14 Tuner https://www.amazon.ca/dp/B00L1LL7DQ/ref=cm_sw_r_cp_apan_glt_i_HMK80QHXSQ24W6TJ9NE3?_encoding=UTF8&psc=1
Or a book of fiddle tunes if he reads music. But the first two ideas are better if he learns by ear.
I'm a fan of Video Speed Controller (this is for firefox, google it for your browser).
It's great, I initially downloaded it for slowing things down to learn them but now I use it a ton to watch youtube videos on 1.5x. Normal speed seems so unnatural to me now.
I know many fiddle players like these ones: https://www.amazon.com/Thomastik-Dominant-Violin-String-Set/dp/B000E1TJDE/ref=pd_lpo_vtph_267_tr_img_2?_encoding=UTF8&psc=1&refRID=YRWAJECZ1SJWXKPAGA2W I think they are a good mid range string and sound good for most people.
40 years ago, I found this record by Tracy Schwartz to be quite helpful:
https://www.amazon.com/Tracy-Schwartz-Fiddle-Country-Record/dp/B00GZ567VA
Also, this one, that he did with Dewey Balfa, for Cajun fiddle
I'm a bit late to this, but Matt Cranitch's Irish fiddle book has extensive bowing notation, which really challenged me when I first picked it up many years ago. It helped me get the techniques like slurring across string changes under my belt, rather than just playing whatever felt easiest https://www.amazon.co.uk/Irish-Fiddle-Book-Traditional-Fiddle-Playing/dp/1900428903
Sidenote - for banjo, the scruggs book actually ain't that great, it's a good introduction but seriously you will get a lot lot more out of Janet Davis "Splitting the Licks", highly highly recommend:
https://www.amazon.com/Mel-Splitting-Licks-Janet-Davis/dp/0786665297
I'm 27 and I started learning fiddle last year. I taught myself for about six months because I had previous music experience. I decided to get an instructor and that was the best decision I ever made. I'm coming up to one year of being taught by my instructor and I already know Westphalia Waltz, Country Waltz, Maple Sugar, Black Velvet Waltz, Big John MacNeil, Devil's Dream, and a few more. - Best tip I can suggest is to make sure you put aside at least 30 minutes per day for practice and violin exercises. These will help you immensely. - Also, for a beginner songbook, I recommend The Fiddle Club from Barrage: https://www.amazon.ca/Fiddle-Club-Collection-1/dp/0786660376 or you can check out this link: http://www.cockmanfamily.com/john/ which has tons of classic fiddle tunes readily available.
If you need any more assistance or questions, please feel free to PM me. Hope this helps!
Banjo player. I picked up this book by Dan Levenson recently. It's clawhammer banjo tablature with a simple (standard notation) melody line. The only reason I brought it up is that it is that it comes with two CD's. Both of them have tracks for all the tunes, but one is solo fiddle (playing more than just the melody obviously) and the other is solo banjo. I didn't know that when I bought it, but I thought it was interesting. Might be of interest if you don't mind learning tunes by ear.
I have a friend that plays fiddle and we teach most stuff to each other by ear. Sometimes I like to go through his books and make a banjo arrangement. But if there's a book that has the work done already, I'd probably want to check it out!