That's a nice pull for a beginner. What do you weigh?
Definitely use a narrower stance like in the video - a bit less than shoulder width. The best guide to how wide to go I've found is to set up as if you're going to jump as high/far as possible. You'll automatically set up in the best position for your body. That's your stance width and foot angle (got that from a Charles Poliquin article). Generally, feet pointing slightly outwards is good, and push your knees out too.
There's a ton of information about how to pull, and its a pretty individual thing beyond the basics so hard to give advice without a video.
For what its worth, the most important bits I've learned so far IMO:
- bar over mid foot at the start
- drag the bar up your legs (so wear thick, long socks)
- pull explosively off the floor without losing position and tightness
- don't spend too long between gripping and pulling, that just makes it harder
- be patient when it feels slow, just keep tight and keep pulling
For programming, if you can add 10 kg per week keep going that way until you stall. Then drop it down to maybe 5 kg per week or even per fortnight.
My own experience with programming for DL is that once I was regularly pulling over 200 kg (I'm around 95 kg now, I was around 85-86 kg then) in training, I needed to back off pulling heavy to once a fortnight in the 85-95% range for maybe five singles (so I'd hit a new max maybe once a month if that). All other pulling was sumo or snatch grip of which I do a fair amount without a belt because its lighter. That's the template I'm still following, but I progressively drop the volume of heavy conventional pulls as I get stronger (currently I'm not looking at a new max more than once every two months). Other people seem to do very well with block pulls and stuff.
Keep your heavier pulls in the 1-3 range.
Also do a lot of rowing and try front squats.