Recently a new page started and it has Girls News~Hello! Project as watch on-demand streams along with other Girls News shows, other idol shows and more.
http://ondemand.pigoo.jp/products/list.php?name=ハロプロFor new shows you need a membership, monthly via credit card costs 1260yen and via prepaid it costs more but you get two-month (90days) membership instead.
Older shows need to be purchased separately (~525yen) and are available for viewing for 14 days from what I understand.
Best is, they seem to accept foreign credit cards, at least mine worked so far.