Click your hub then select the "edit" button. Once there, select an Amazon capsule. From there, you can "choose a specific product" or "choose keywords".
If you choose the first one, you have to add the Amazon URL, ASIN or ISBN of your chosen product. To get this, you have to go to the Amazon site and find the product that you want to add to your hub.
Once you have the product URL, just put it on the Amazon capsule then save said capsule. The product should now be featured in your hub.
If you chose the second option, just type in a keyword in the search area of the capsule then select the product area of your choice. Click the "preview Amazon result" to see if the product that shows up is the one that you want to feature in your hub. Save the capsule and said product should show up in your hub.
I don't know about any video tutorials but if you check the HubPages learning center, there are a lot of hubs there that explain how HubPages works. Here's the link for that: http://hubpages.com/learningcenter/contents . Hope this helped.