Exceeding VLO and by how much is too much?
The gear itself and its attachments being pretty beefy, you can't really damage the gear legs extending them at any speed the airplane can fly at.

The limitations usually relate to the doors, which are more delicate, and having large surface area, are far more affected by air loads.  So the main effect of exceeding a gear speed limitation is the risk of bending or distorting, or in extreme cases blowing off, gear doors.  

If you have a minor exceedance of 10kt, I'd just give a visual check of the doors later.  If it was a major exceedance of 20kt or more a tech should look at it. The doors may look ok at a glance, but if they are deformed they can prevent the gear from extending next time, if, say a distorted door's edge overlaps the opening and slips past on retraction but hangs up on extension.

Extension/retraction speeds, VLO, or speed you can operate the gear selector, and maximum operating speed with the gear down, VLE, or speed you can fly with the gear down and locked, are sometimes different (VLO is normally lower than VLE if they are) because there is a limit speed that affects the gear while in transit, whereas once down and locked you can speed up.  This can be from sequenced gear doors that are only open during the extension/retraction cycle, or a limitation on the ability of the hydraulic system to retract, say, a forward retracting nose gear against air loads (a speed limitation could also be related to a stability and control issue as well). 

I dimly recall from my multi training days (but not totally sure) that the limitation on the Seminole was related to its rather weak hydraulic pump which had to work too hard above a certain speed, stalling the pump or popping the CB, something like that.  Some amount of safety margin would have been applied to the speed the problem was happening at, giving the published limitation of 109.