Googlefish translated link to Eagles’ press video page at niconico.jp.
Aggravtingly, the Yahoo.jp NPB news page and the corresponding Eagles schedule resist the Googlefish.
There does not appear to be an iPad video player app for niconico.jp available in the App store, and attempting to play the videos once registered presents what appears to be a technical compatibility note that mentions OS X, IE, Windows, and Flash, but not iOS.
Additionally, I was able to register at both the English-language niconico.com and the Japanese-language niconico.jp with the same username but different associated emails. I suspect that this indicates a fully-segregated user-management and content system. Backing up that speculation is the fact that the active English-language userid was not accepted as a login from the Bionic Eagles page.
In the past, it seems that the Yahoo NPB Pacific League portal was one of the ways to view the games. The playback was geo-restricted in some way, however.
I have yet to try the niconico.jp playback of the last-season videos on a desktop operating system.

UPDATE: if I am logged in at niconico, the page won’t render in translation. Proceeding untranslated, each individual video will not play despite my being logged in, something I assume which represents geo-blocking.

Therefore, my next steps are to work through the use of proxy servers to provide in-Japan IP spoofing.

As I have been hacking away at this, I am put in mind of my fascination with manual tuning of scrambled pay-cable channels as a kid. My parents wouldn’t pay for HBO as a part of their cable package, and the methodology used to keep premium channels out of view was an analog variable transmission scrambler, or something. The end result was if you manually wiggled the fine tune knobs on the TV and the cable box at the same time, you could occasionally get glimpses of partially unscrambled content.

I would do this for hours, not because of the content, but because I couldn’t get to the content. It seems clear to me that I am in the same sort of dynamic here.