Which older version of YouTube for HTC Hero? I just put CM7 on my HTC Hero. Now I'm in the process of isntalling all the apps and the problem is that the YT app that's on the market is not compatible with HTC Hero. Does anyone have a clue which is the oldest supported YT app for Hero, and where I might get it?
What you need to download and install is called GApps, which is a package with all the Google applications that come built in with Android, but those are flashable and you can't just install them.

I suggest you to take a look at [ROM] Hero CyanogenMod 7 Nightlys-Android 2.3.2 Gingerbread (2011-02-27), download the GApps provided there(gapps-gb-20110120-signed.zip) and flash that using the Install update.zip on your unlocked bootloader menu.