What it says:
You retain ownership to the Video Content You submit for inclusion into the Yahoo! Video Service. However, by submitting Your Video Content to Yahoo!, You hereby grant Yahoo! the following worldwide, royalty-free, non-exclusive, sublicensable and transferable rights and licenses:
a. to host, cache, store, archive, index, crawl, create algorithms based thereon, modify or transcode the Video Content to appropriate media formats, standards or mediums as part of the Yahoo! Video Service;
b. to use, distribute, reproduce, modify, remix, excerpt, adapt, prepare derivative works of, publicly perform and publicly display the Video Content on the Yahoo! Video Service or on any Yahoo! property, including in connection with any distribution or syndication arrangement thereof with third parties or third party sites, in any media format or medium and through any media channels; and
c. to use Your Video Content for advertising, promotional or commercial purposes, including without limitation, the right to publicly display, perform, reproduce and distribute Your Video Content in any media format or medium and through any media channels.
By submitting Your Video Content for inclusion into the Yahoo! Video Service, you also grant the following use of and rights to Your Video Content to others: (i) the non-exclusive license to access Your Video Content through the Yahoo! Video Service; (ii) the ability for Yahoo! registered users ('Yahoo! Users') to rate, review, comment on and tag Your Video Content; (iii) the ability to embed Yahoo!'s video player with Your Video Content on their web site; (iv) the ability for Yahoo! Users to send and distribute Your Video Content via E-mail or Instant Messenger; (v) the ability to access Your Video Content via Yahoo!'s web service APIs or via RSS or any similar XML or related feeds; and (vi) the non-exclusive license to use, reproduce, distribute, remix, prepare derivative works of and compilations, display and perform Your Video Content as permitted through the functionality of the Yahoo! Video Service and under these Additional Terms and the TOS.
The foregoing licenses granted by You shall terminate once You remove or delete Your Video Content from the Yahoo! Video Service.