Because there are so many factors involved in search engine optimization, it's very hard to isolate which one in particular is due to a rise or fall in rankings. Still, you can make educated guesses from what you observe. Which is what I'm going to do now:

I have a blog about Perth that's been going a year or so. It spent quite a while about half way down the first page of Google for results for "Perth blog". Then it slowly dropped down the rankings and wound up on the bottom of the second page. It stayed there for a few months.

Now just recently I started uploading videos to YouTube. So far, they've all been of various Perth landmarks. And I've included a link to that particular blog with each video. I've also put its URL in the main profile section.

Now I know that all the links you get from YouTube these days are "nofollow". This means that search engines don't "follow" where they're pointing to and reward that particular site with higher rankings in the SERPs. That said, there does seem to be a belief among many in the SEO field that they might carry some small benefit ranking wise, particularly if the links are located on big quality sites.

This interpretation seems to have been confirmed by my own experience, because a couple of weeks after I put those links on YouTube my blog ended up on the top of the second page for searches for "Perth blog".

After this, in the last week or so, I established Google Plus authorship of that particular blog. This seems to have resulted in another boost for it. Now, I'm in the middle of the first page for searches for "Perth blog".

Maybe this won't last. I'll just have to wait and see. But I'm pretty sure that the Google Plus factor was what caused it, since it was a substantial change that occurred suddenly.

So in my opinion you should start putting videos on YouTube and link your Google Plus account to your blog as soon as possible.

I have only started getting into YouTube recently. But I'm glad I did. It's surprisingly easy to make little videos that will be of interest for viewers. The other day, for example, I made three short ones in the Perth CBD that I uploaded soon after. That took me only an hour or so of filming.

It should be remembered that YouTube is a massively popular search engine in its own right. Even a couple of years ago it was getting billions of searches a month.

So you can get ideas for what kind of videos to make much as you would from Google. Just use the drop down suggestion box, for example.

You can also use the free keyword tool, confident in the knowledge that keywords that are often searched in Google itself will also be popular in YouTube. (There is a similar tool for the site itself. But the data isn't that comprehensive.) 

For example, I knew that the term "Perth Arena" got a reasonable number of searches on Google. So I made a quick video of the structure and uploaded that a few days ago, making sure to use the term in the title. It's on the first page of results for those keywords, and it's had a few views already.

Now I know from my blog stats that it's easy to rank for local terms. And that brings in really good local traffic too. So I'm going to keep generating video content to get those clicks onto my blog about Perth.

I recommend that others wanting local traffic do the same. If you can find a local angle, then make a video about it. But don't just make ads. Make content that people want to share.

For example, if you're builder in Perth, you could make a video about how to build a house for the city's particular conditions. You could then get your local keyword in there. And you'd still be creating interesting and useful content.

Or say you have a cafe in Newtown. You could just wander down the street filming the buildings and crowds giving an idea of the whole atmosphere of the place. And you should put the keywords "Newtown" and "cafes" in your video title. There'd be a lot of people searching for them on Youtube. Even if your video didn't get on page one straightaway, as long as it was shareable it would crawl up the rankings and you'd be sure to get some targeted traffic to the site you have included in the description.