If you ask me which one SEO technique can give desired results then i would undoubtedly suggest Video marketing, especially through Youtube.
I ran an experimental website which contains links to free downloads of software, ebooks, movies etc., It is a free domain (.tk) running on free hosting. I exclusively used Youtube strategy. This website consistently ranked within top 10 google search results for relevant keywords.
I will explain you the strategy i used. Please note that i
1. First select any digital product which can be downloadable and is in demand.
2. Add a phrase "free download" to this product and do keyword research using google keyword tool.
3. Select a keyword which is having large number of search number and try to find the number of websites competing exactly to this keyword (by using allintitle and inurl search queries). I select keywords which returns less than 5000 websites. The keywords shall be related to the products.
4. Then download some snapshots of this product and note the description and features of this product.
5. Make a video using Windows Movie Maker adding the URL to your website and snapshots downloaded. The length of the video should be more than 45 seconds. Instead of adding music record the description and features of the product and add to the video.
6. Add the selected keyword to title of the video. Add the phrase "free full download" to the title.
7. Add the link to your website on the first line (do not forget to add
http://, otherwise the link will not be clickable). Make sure that the link to your website is a Permalink with the exact selected keyword.
8.. Add this keyword and the phrase 2-3 times in the description. Also add the description and features in the description.
9. Add the selected keywords, to the tag of the video.
10. Wait for a week before and then check. Your video will be in google top 10 for the given keyword.
11. If needed submit the same video to other video sharing websites and follow the same strategy.
Additional strategy:
1. Find the tags of the related videos to your product in Youtube and add them to your tags.
2. Add your video as a response to other videos related to your product.