I generally prefer written reviews - I almost NEVER watch video reviews, and here's why:

+ Still pictures are clearer/easier to see than video
+ Some video reviewers have poor public speaking skills (e.g. poor enunciation, lack of voice projection, poor intonation etc.); who wants to listen to someone mumbling??
+ But my #1 gripe about most video reviewers over text reviewers is that most video reviewers DON'T REVIEW TOYS!

re-view /rɪˈvyu/
noun
a critical article or report; critique; evaluation

That's right... critical. You can't be critical when you don't criticise the toy! Most video reviews I see remind me of that Simpsons episode when Homer becomes a food critic, and gives EVERY restaurant flawlessly positive reviews ("What the hell is three thumbs up?!"), and as a result he had _no_ credibility as a reviewer. And that's precisely how I find most video reviewers. If you're going to say every toy is "awesome!" all the time - especially without much (if any) justification, then THAT'S NOT A REVIEW!

There are some reviewers who are quite positive, like Ben Yee... but he's always careful in explicitly justifying why he's positive about a toy and gives it a good rating. Look at his review of Injector, IMO one of the worst toys ever made. He gives it a B+ or something. But he explains why -- in his opinion the execution of the toy isn't so good, but he can admire the effort that went into crafting it. I disagree, I still think it's a craphouse toy -- but I can see where Ben's coming from because he's justified his opinion. Opinions are never right or wrong, but you do need to provide some form of justification in order to validate them. And most text reviewers do this well.

Most video reviews are like...
"This is X Transformer, it looks like this, it transforms like this, it has these features, I like this toy and I'm so happy/excited to have it -- therefore it's AWESOME!" No wait, just because you like the toy - on its own - is not a reason for its awesomeness. Often we do like toys that we know are crap! I knew someone whose favourite toy is G1 Blot, simply because it was his first Transformer, so there's that sentimental emotional attachment to it. And that's fine, but nobody's gonna use that reason as an objective means of saying, "And therefore it's an awesome toy!"

Some video "reviews" are more like boast videos. Especially the ones that "review" toys that aren't even out anywhere yet, and are likely to be stolen from a factory. They sound more like "Look at me, I'm awesome cos I have this toy and you don't! This toy is awesome and it makes me awesome for having it!" Yes, everyone likes to boast about having a cool toy - that's what acquisition threads and collection pic threads are for. Or make a video showing off your collection or a toy... but don't call it a "review." (-_-) Call it a "showcase" video, because that's really what most of them are.

And even when you watch people try to review toys, I find they don't do a good job. One thing that gets me is how they just review them as display pieces. Hello? These are toys -- action figures! Evaluating their play value is essential! I used to post text reviews on a consumer product web site, and I used to get a lot of positive feedback not from collectors, but from parents trying to decide which toy to buy for their children. Because at the end of the day, that's still the majority demographic of people who buy Transformers: kids. I can't stand reviewers that say something like, while this toy sucks to play with, it still displays well and therefore gives it a positive review. That's like giving a car a positive review because it has a beautiful body, but craphouse performance, or a positive review for a dish that's beautifully presented but tastes like crap. Yes, presentation and beauty is important, but so is playability. People need to review toys like say a food critic (like say on Masterchef). At first you examine the physical look of the toy, but the main crux of the review should be on the design, engineering and most importantly, the playability - because that is the core function of a toy.

There are _some_ good video reviewers out there, but most that I come across aren't. On the whole I find text reviewers are better at reviewing toys than the average video "reviewer" who tends to showcase/boast about their toys. The only thing I use video reviews for now is when I get stuck on a transformation. I must say that's the one good thing videos can do that still pictures or text can't (and as 5FDP said, especially when Hasbro gives us really poorly made instructions!)