@MushroomCake28 makes all the necessary points from a business standpoint I think so no need to rehash those
As you asked I'll post my advice here, though this is more advice geared towards how to handle a dev-log from a more interacting with your audience standpoint, and also considering we're not a triple A studio ;
First off, be clear about your own expectations and intentions with the dev-log. Don't 'go dark' or leave your viewers in the dark at any point but be clear about why you might nor update for a while, concerns you might be facing, etc. give people explanation. Keep expectations realistic for both you and your audience.
Second, when it comes to presentation ; it's good to have visuals as they help hook an audience and convey your ideas more clearly, as well as a faster way to show progress, however they are not the Holy Grail some ppl make them out to be. In the end your audience is watching because they are interested in your project and its status and not in the fact you're live-streaming from E3 for example. (I've had this with triple A studios having a devlog and I find myself yelling at the screen "who cares? talk about the game already!"). I much rather read a whole wall of text that holds my interest then watch a bunch of flashy graphics that tell me nothing at all.
Thirdly, (especially when on platforms like YouTube and alike) prepare to receive some annoying things thrown at you from ppl who are there just to throw crap around. Don't let it get to you and instead look at who gives you feedback, what kind of person are they? and why are they watching? Remember why you start a dev-log and don't get sidetracked by idiots or ppl who's opinion is either irrelevant or not aimed at the project at all.
Lastly, have fun! If you find yourself not having fun doing it then you might need to reconsider if that part of it is for you or if your timing is correct. Never be afraid to reconsider and re-evaluate what you are doing.
And that's the limit of my wisdom

As always, remember we are all wrong anyway xD