At this URL there is an embedded video player. The swf filename is pp_msr_player.swf and apparently it can take an XML-based playlist.
Is this an in-house developed flash video player or is this particular player available somewhere else?
Where I can get the particular skin used in it, preferably formatted for flowplayer (http://www.flowplayer.org/)?
It looks like a custom Flash application. The embedded .swf is passed a bunch of variable values in the URL. This technique is described in the Adobe article Different approaches to setting variables. The URL that is used in the page is /cms_content/US/en_US/files/merchant/pp_msr_player.swf?config=/cms_content/US/en_US/files/merchant/pp_msr_ec_config.xml&debug=false. config and debug are variables defined within the Flash application. I don't know much about Flash but it looks like a simple application that retrieves a simple XML configuration file.
I fetched the configuration file with curl and it isn't that surprising:
<?xml version="1.0" encoding="UTF-8"?>
<demo project="Mkt-Demo:MerchantServices" name="ExpressCheckout_v1"
pagename="" country="US" language="en_us" version="PPCustomPlayerv1_Flash9">
<chapters path="">
<chapter name="CheckoutExpress" file="ExpressCheckout122209b.flv" dur="125"/>
</chapters>
</demo>
My guess is that this is a custom Flash application developed by someone inside of PayPal written for the purpose of demos. Chances are that the skin is product and property of PayPal and developed by their art department.