The problem with video or audio is that such information is not easily referenced; you have to go from beginning to end, and then, if you want to go back to a specific step later on, you need to keep clicking on the timeline until you reach something that looks like what you want. And then hope you found the right spot. This is as opposed to blogs and other forms of written content, which are usually separated be headings, and are easily skimmed through until you find what you want.
What all this means is that anything requiring the person to perfectly follow all steps from A to Z will benefit from the video treatment. However, anything that can be modified as appropriate should be presented in a text-based way, so that the person can skim through and find the salient parts of the post.
An example of something that benefits from video would be a video game walkthrough; by showing the action on-screen, the viewer will be able to see the sequence of events, both the actions of the player, and the reaction of the game engine and AIs.
An example of something that benefits from a text-based blog would be a tutorial for a program like Photoshop, or the GIMP. These programs are complex, and no video can possibly cover everything, and often people desire things on these programs that require a collection of different actions. Sometimes, all the actions are required, sometimes, they want to get to a point, and then diverge. Or maybe they simply want to refer to step 5, because it might be something that would work with their current project. For whatever reason, trying to find that step in a 30- to 50-minute YouTube video is downright frustrating.