When content is shared there is a URL parameter that looks like &intk=89743472839 (or another number). With this integration key we capture the user that shared it and the contact or lead it was sent to.
To generate this same tracking ability you can take your base URL to the presentation and add &int1={!User.Id}&int2={!Contact.Id}{!Lead.Id}&int3={!Account.Id}{!Opportunity.Id}{!Campaign.Id}
So, if you have an SFDC email template that you want to use for sharing a piece of content and the link to the presentation is located in the template you would just add the above string to the template. When that template is selected when sending the content. SFDC will populate the data and that viewing data will sync back to Salesforce after it has been viewed by the recipient.
Example: your link to the presentation might be: https://www.brainshark.com/test/vu?pi=750405
In the template the link would look like this :
https://www.brainshark.com/test/vu?pi=750405&int1={!User.Id}&int2={!Contact.Id}{!Lead.Id}&int3={!Account.Id}{!Opportunity.Id}{!Campaign.Id}