When you are running an Intent Lead Campaign or a Content Lead Subscription you will see the "Intent" option appear under the Marketo Programs section in your Connector. This option allows you to connect the Intent lead portion of your campaign to a specific Marketo Program- in other words, it allows you to partition the Intent Leads (specifically) for attribution and lead scoring purposes.
By clicking "Connect", you'll see the option to connect this Campaign directly to an existing Marketo Program.
Note: BrightTALK requires that the Program type for Intent Leads be "Default." This is because these leads are not webinar leads and should be treated separately from your other BrightTALK lead types. The status for these leads can be changed from the "Map Program Statuses" UI (otherwise it defaults to "Engaged").
Note 2: For Content Lead Subscriptions, the "Intent" option will only pass Intent Leads. It will not send your Content leads to that Program (those are mapped via their individual webinars).