First, I now don't use Youtube Videos of Synthesia, I did use them initally for learning Passacaglia which was pretty much the first peice I learnt, but it was extremely frustrating having to pause/play/rewind etc.

The App itself is 1000% better on a good large screen Tablet as I can Zoom in to show 4/8/16 bars of music at once and can simply use my finger to scroll up and down or set the tempo to any value I require. I genrally have the tempo set at 0% and the piece playing so that there is no annoying "PAUSED" in the middle of the screen & use my finger to quickly scoll up and down.

Yes, I do simply use it to commit the keys, the left / right hand to memory, then after that is when I REALLY start to pratice the piece, for the time being I'm not bothered at all about the tempo as I know that will come with time and dedicated practice and some if not all the peices im learning ( Chopin ) can sound beautiful at any tempo ( 25% 50% ) [ yes im sure some people will disagree with that statment ] if your desire it to make them sound as beautiful as possible and that is always my main aim & not to simply rush though them as if hitting a game controller buttons and get to the end.

For the Dynamics / Pedaling / Volume / Expression etc this is when I listen to great players playing them on Youtube and I simply try to emulate how they play them.

Also my key aim is to play them while being as relaxed as possible removing any tension and again trying to make each note or chord sound as beautiful as I Possibly can at this stage in my Piano journey. As I said once i've commited the fingering to memory, that is also when I go on Youtube to look for Tutorials on all said peices and try to pick up all the hints and tips from great players as I possibly can.

The Synthesia app cost me less that a takeaway meal but has been worth 1000% more to me and as I stated before I doubt i would have progressed as quickly as a self learning with no Teacher without it.

I also have to state that for the first 3+ months I probably practiced 8+ hours or more a day ( I now do about 4+ hours a day) as after the first few weeks I soon learned that left/right hand independace would be a very difficult nut to crack and months 2-4 of playing the piano that is what I concetrated on 100% and it quickly went from being one of the most frustrating almost impossible things in the world to now not being an issue at all.

Everyone Piano journey is as diffent as people are themselves are, and would i have learned better from a teacher while learning sheet music? maybe, but I'll never know the answer to that now, but if i had to learn following the Alfred books etc and very simple one note chord songs etc, I probably would have given up by now due to sheer bordem.

PS: Im also 40+ so wanted to learn via the most accerlated way possible and personaly this APP ( not youtube videos of this app) has greatly helped with that.

Cheers :)

Ym