There are some wonderful Mexican music tutorial videos for FIDDLERS - even for music played by Mariachi Bands!  Some are indepth tutorials while others are play-alongs with notation & slowed down sections.  

Here's some of my favorites to start with!  ...if you play Viola, or Cello, and you want to learn some of these tunes, BUT need help transposing music down lower into Alto, or Bass Clef  - please ask! 

Aaron Piedra - Playlist of Tutorials in English (15) - GREAT (VERY EASY to follow) Mariachi Violin tutorials, with rolling notation, extra tips (in English) & links to sheet music! 

The sheet music is available for free download and is located in the comment section to make it easier to find. I try to approach each tutorial as if I am showing/teaching an intermediate level violinist. I will show you how to play this song by demonstrating short examples, talking about the notes/positions, and sometimes talking about the specific style required. I may review some fundamentals and techniques along the way, but I try to explain what I am talking about as best as I can. If you are confused about any part, or have any questions always feel free to ask me. [Aaron Piedra]

Tonatiuh Barreras (YT Channel) is a wonderful violinist in Sonora.  His tutorials feature slowed down play-alongs with rolling notation.  I think he sets a GREAT example to follow - by watching, listening to him play & following along with the notation. 

Mariachi Music for Violin at 8NOTES - some stereotypical play-along scores, PDF, midi, transpositions & parts sometimes available. 

JUAN FILOMARINO PARTITURAS Y TUTORIALES (YT Channel) - GREAT tutorials, I really like these.  They are in Spanish, but unlike some channels, the translation setting WORKS wonderfully! 

If anyone has other preferences - please share!  

Related Threads: 

Mexican Music - It isn’t All Mariachi Thread 

Mexican, Hispanic and Latin American Thread