Bob said

@Ferenc Simon, I think you're trying to confuse me, next  you'll be telling me there's no Santa Claus or Father Christmas

Bob  

That's right! And Rudolf is a turtle!

Nice one Bob!

Try the following things:

 - modify your grip a bit so that the stick is pulled up more towards your palm and that your index finger is actually touching it at the second joint and not the first one. It will look and feel less like you're trying to drop something and more like the bow is an extension of your hand. 

 - the above will give you much more control over the bow and less things will be left to random chance, which will allow you to really feel the exact weight you're putting on throughout the whole bow and you should be able to get a nice even tone every time, even when your bowing is slightly crooked

 - the bow grip changes will only work properly if you loosen up your wrist. try grabbing the bow with the above mentioned 'tighter' grip and then with your other hand grab the stick somewhere at the middle and try turning / wiggling it to see if your wrist is lose enough to follow the movement, instead of the actual stick being lose in your grip (in the above video sometimes the stick is turning on its own from within your grip, without the hand following that's why I'm suggesting a tighter grip) 

 - it's easier to learn the proper wrist motions if you start with the bow on the strings close to the frog and intentionally bend your wrist in an exaggerated way to make the bow parallel with the bridge, then do the down bow at the same time extending your wrist to compensate for the arching movement of the forearm (this will keep the bow parallel throughout the whole motion), then come back slowly with the up bow and about halfway through remind yourself to start bending the wrist so you come back to the starting position. Also slightly rotate forward when getting closer to the frog. That will give you a bow tilt but at the same time reduces the wrist flexibility required to keep the bow straight. 

 - and last but not least, try to sit a bit straighter on the chair and raise the scroll of the violin so the actual strings are parallel to the ground and not the violin (sometimes the tip of your bow is simply pulled forward by gravity...) 

If the tighter bow grip doesn't work out, you can always switch back, but I think you might like it  

Keep up the good work!

Yes, I do the same.. when I'm trying to really focus on something else (like a sheet of music) some of the movements are getting 'skipped' or just performed in a lazy way. 

I also understand the back issues all too well.  Surprisingly enough, even though I'm barely 30.. I have plenty of 'anti-violin' pain already (stuff that interferes with playing). I play while sitting most of the time as well.. however in my case it's due to messed up vertebrae and a bunch of shoulder pain so it doesn't really make much difference whether I'm standing or sitting, unless I can lean back and get support from the chair. Which is what I do most of the time when learning new stuff, but when I actually want to perform them I stand up, since it's much easier for me to bring the elbow in under the violin and also to do vibrato while standing. (Well.. that.. and also the fact that posting a critique video where I play leaned back in a gaming chair and possibly even with my feet on the table would make for some really interesting critique comments :))))) ) 

In any case what you can probably do is to raise the left elbow together with the violin and that would probably solve many of the issues.. hmm maybe raise the sheet stand to eye level too? that might solve some of your posture problems, since you won't have to be looking down.

Bob I think that's pretty much the curse of everyone here.. Once the camera starts rolling it's like my arms are made of concrete I start forgetting what I already learned... and so on.. 

Generally I'm trying to account for some of that when replying to critique videos... and I think others kind of do the same, since they experience the same when recording their videos That's why I'm usually not bothering much with the really small stuff.. like the occasional crooked bow, I mean you probably see those as well even before posting the video. Instead I try to think of tips that you may or may not have thought of which might reduce the chance of stuff going wrong in the first place. They might not work for you even though some of these have worked for me  

Also here I am talking about bow grips when I just uploaded a video where I have a pretty wild one lol. I'm actually using the grip I suggested for you (closer to the palm), but I messed up when I first grabbed the stick as it was tilted to begin with.. so instead of adjusting it like a normal person would have done... I decided to roll with it, out of fear of messing up in front of the camera... so I had to overly flatten my wrist when at the tip of the bow to compensate the rotation :)))) Fun stuff always happen when you play for a camera... 

I guess we should just be happy when we can do stuff properly off camera, since the violin is more about playing it anyway and not just recording it and just hope that in time we'll get used to the 'spotlight'  

Cheers