You're not alone, there is often confusion about the Forwarding Virtual Server, and what role it serves in an F5 LTM. Not having watched the video in question, I can only speculate on exactly what Keith Barker said/why he said it. However, knowing the high quality of his other training videos, I can assume that the following is what he was driving at.
Essentially, think of it this way:
- All forwarding and policy decisions are made by the LTM services (Virtual Servers, SNAT, and NAT). These configurations act on the traffic at ingress.
- Final routing decisions are made by the routing table of the device, once the LTM services are done with a particular piece of traffic. The routing table acts on the traffic at egress.
See this very helpful diagram of the traffic flow through an F5 LTM. You will notice that new traffic is matched against Virtual Servers, SNAT, and NAT for all actions.
Remember what the F5 LTM is for, it is a Load Balancer and is designed to explicitly proxy connections through it's Virtual Server constructs.
In order to have it simply pass traffic, you can configure a "Default" Forwarding Virtual Server that listens on all addresses and on all ports. This allows you to somewhat cheat the system, and have it transfer traffic through the device, but not to a pool of servers.
This is commonly used to allow traffic to flow from the servers behind the LTM, outbound to the world for patching, etc. In addition, if you wanted to do more than simply route that traffic (for example to apply any of the dozens of wonderful "knobs" that the LTM provides such as TCP fixup or an iRule), you could do that on a Forwarding Virtual Server.
You can certainly configure a standard static IP route with the following command in TMSH:
create net route <route destination/mask> gw <IP addres>
However, without LTM configuration of some sort (Virtual Server, Forwarding Virtual Server, SNAT, or NAT), the traffic would simply be dropped and never even reach the point of doing a route-lookup against the routing table. The F5 LTM is a Default Deny device, it will not forward traffic that you have not explicitly permitted/configured.
Finally, for more information on Forwarding Virtual Servers, read SOL7595 and for more information on Static Routing on the LTM, read SOL13833.