This was the OID I was looking for. Thanks!
I still had to figure out how to query the route table pertaining to a specific routing-instance and the solution is to reference the routing-instance as part of the community string as follows:
snmpwalk -v <version> -c <routing-instance>@<community> <hostname/IP> <OID>
The key is to put the routing-instance name before the community string separated by the "@" sign.
Example: snmpwalk -v 2c -c iptv@public 10.100.100.1 126.96.36.199.188.8.131.52.2
I also found OIDs relating to IGMP and PIM.