The video you saw with the instruction to push your elbow in when going down the strings and pull it up when going up sounds intriguing. Trying out new approaches can be a fantastic way to improve your skills.

As for whether you should put a lot of effort into learning this technique, it ultimately depends on your personal preference and goals as a guitarist. Experimenting with different techniques can help you find what works best for you and makes playing more enjoyable.

Since you mainly play acoustic guitar, it's worth noting that different techniques may have varying impacts on your sound and overall playing style. So, it's definitely worth exploring and spending some time practicing this technique to see if it suits your playing style and enhances your sound.

Regarding strumming, the elbow movement technique could apply to some extent, especially if you're doing intricate strumming patterns that involve quick changes between strings. However, strumming typically involves a mix of wrist, forearm, and elbow movements, depending on the pattern and the sound you want to achieve.

Remember, there's no right or wrong way to play the guitar – it's all about finding what feels comfortable and helps you produce the sound you desire. So, don't be afraid to experiment and see how this technique fits into your playing routine.

Keep up the enthusiasm and dedication to improving your guitar skills. Every new technique you learn adds a little more depth and versatility to your playing.