I've not used Installer for a very, very long time. If it's anything like Cydia now, you'll have to go into Installer, find the app you installed, and somewhere there should be an option to uninstall it.
You cannot delete Jailbroken apps as you would normal ones, you have to uninstall them from wherever you got them from.
In future, I recommend not using Installer if you're on 2.0 or above, since it's all basically dead. Use Cydia from now on, and if you want a free video recording app use Cycorder.