Hey immecohen,

Here are a couple of solutions you might try:

1 - If this is just for an exercise, try starting on higher frets. You could even put a capo on the 5th fret and "add 5" to whatever fret number is in the exercise. So frets 1, 2, 3, 4 would now be 6, 7, 8, 9. As it gets easier there, try moving the capo down one fret at a time, as you get better at stretching your fingers farther. However, the notes you'll play on those higher frets will be different pitches from the video you're watching. But this way the it's a gradual stretch. 

2 - It might be a financial hassle, but they do make smaller scale guitars. Look up 3/4 scale acoustics. https://www.guitarworld.com/features/best-three-quarter-acoustic-guitars There's no law saying you need to play a full-size guitar. 

Hope those ideas might help!

-Carl.