Amazon.com is pulling out the stops this month with a new monthly Prime membership.

The $7.99 monthly service includes access to Amazon.com's library of streaming video content. By adding a monthly option, Amazon's positioning it as more of a direct competitor to the video services of Netflix and Hulu Plus with similar monthly fees.

But access to a pool of online video is just one component of Amazon's Prime service. Prime is mostly designed to encourage frequent shopping at the site, by providing "free" two-day shipping to subscribers as well as the video service and access to Kindle loaner material.

Selling and shipping merchandise is still Amazon's biggest business and streaming video is miniscule by comparison.

Adding a more accessible monthly Prime option just before the busiest retail season of the year could substantially boost Amazon's merchandise sales.

It will especially appeal to careful shoppers who figure out that they can now pay just $7.99 and get free two-day shipping on all the gifts they buy at Amazon.com.