I doubt they are 'resistors' in the circuit as these would not work- if they went cheap they are probably zener diodes with a zener voltage just above what they are expecting or have tested maximum Vf of the LED's they are using. The LED fails (open) and driver voltage begins to approach the clamp level of the driver circuit, the zener exceeds it's zener breakdown voltage and begins carrying current, and all is well for the remaining LED's in the series string. When the LED is operating correctly, the voltage across the zener device never reaches it's breakdown voltage- it just sits there.
If they went expensive they would be using semiconductor clamps designed specifically for HBLED purposes- but again, these devices are not cheap, and to do it right you would be using a lot of them, one across each LED die, or best case maybe 1 protection device across 3 LED dies- still a lot of $$$. They work something like a glorified SCR, with enhanced functionality to cover virtually all failure modes of the LED as well as giving reasonable protection against ESD events.
Aside from offering limited protection, the real problem with the zener scheme is that these zener devices may not be able to carry the bypass current and may eventually fail as well- they typically aren't designed to handle these current levels long term- this is not an issue you would associate with a device based on an SCR. If you are looking at your light and the device is a little tubular, round looking thing, it is probably most certainly a zener- if it is a little black box then it could be either, as zeners come in a host of packaging styles but the SCR type protector is almost always a little black box.
