Not a twin-arc HPS but your average HPS probably Eco.
http://www.youtube.com/watch?v=EU-v8G0GR-w

Strange!

Its one of those instant re-strike ones!

you know something, this could be a lower wattage one......I notice my 35 watt and 50 watt and sometimes 70 watt ones would do the same thing....sometimes..if you flip it on and off in short time between flipping it on and off

HPS ignitors are usually divided between 35-150W and 150-1000W aren't they? So that means a 35W lamp has an ignitor capable of lighting a 150W lamp, and so the cool down period (if any, I don't know) would be shorter.

HPS ignitors are usually divided between 35-150W and 150-1000W aren't they? So that means a 35W lamp has an ignitor capable of lighting a 150W lamp, and so the cool down period (if any, I don't know) would be shorter.

For US area the division is mainly due to two lamp arc voltage ranges in use in US:
- ~55V for use with series choke ballast, so OCV = 120V (35..150W). These require ignitors with triggering voltage around 100V.
- 70..140V for use with transformer ballasts with OCV 220V and above (150..1000W). These require ignitors with 210..240V triggering voltage (and higher pulse voltage as well).
Beware of 150W lamps, as these are in both versions (50V as well as 80V) and they are not interchangeable.

Operating "low wattage" (100V) ignitor in higher wattage ballast might result to two issues:
1. The ignition peak voltage would be below specification (usually not as big problem, only restrike time would be longer)
2. When the lamp warmup, the arc voltage would rise above the ignititor trigger one, so the ignitor would start to fire into running lamp and fail soon.

Opposite, operating "high wattage" (210V) ignitor in low wattage ballast would lead to ignitor not working, as the ballast OCV would not be sufficient to trigger it.

I think there are 4 possibilities
1- the lamp isn't fully warmed up (notice the very yellow color)
2- the ignitor is made for instant restrike and produces higher voltage pulses
3- the lamp is the MV "retrofit" one and starts easier with an ignitor.
4- the lamp simply fires up with normal ignitor, that could happen with the very low wattage ones.

bulelights: Special instant restrike ignitors are available only for several types of MH lamps (Usually short arc MH lamps, automotive xenon MH lamps and the old very high wattage european tubular MH lamps). HPS can often instant restrike with its regular electronic ignitor.
New HPS lamps usually have no cooling down period.
Argon-neon MV retrofit HPSs, i don't know if an additional ignitor is good to them.
There is two type of external electronic ignitors for HPS and MH lamps: The old semiparallel and the modern superimposed.

There is two type of external electronic ignitors for HPS and MH lamps: The old semiparallel and the modern superimposed.

I would not call the semiparallel "old" and the superimposed "new". Semiparallel are mostly (in EU) "long range" ignitors for remote ballasts, because the "50Hz" ballast choke might serve as pulse transformer for ignitors working to low frequency range (starting pulse width in 10's of us), when the high wiring capacitance to the lamp does not attenuate the starting pulse.
Superimposed are only short range ignitors, as the secondary of the pulse transformer has to handle the full lamp current, so should be made of thick and not as long wire, what mean such transformer is able to work really only on high frequencies (ignition pulse width 1us and below), so can not work with longer wiring. However they separate the high voltage generation from the ballast, so there is at first no risk of ignitor pulser vs ballast tap ratio mismatch and as second the ballast can tolerate quite significant insulation degradation, as it does not have to handle the high voltage.
In US nearly all ignition systems on magnetic ballasts are of semiparallel configuration (even when using low energy, so short range pulsers), as it is cheaper system.

On electronic ballasts (except those cheap high frequency HPS inverters used with 70W and below) is used only the superimposed ignitor, as the ballasting is done by DCDC converter (controlling the power delivery) followed by transistor bridge swapping the lamp polarity each few ms. This can not tolerate more then normal operating internal DC bus voltage (~400V with, ~300V without PFC), so the only option is connect the HV source (pulse transformer secondary) in series with the output.
But the whole ignitor is integrated into the ballast box, so externally the "user" only connect the lamp. This configuration i do not consider as good, as it enforce to place the ballast (temperature sensitive) close to the lamp, where is quite lot of heat. Separating the ignitor (and it is of no technical issue designing the ballast so, it would be compatible with "generic" superimposed ignitors) would allow placing the ballast remotely and keeping only the ignitor close to the lamp (the wire length limit is dictated solely by the ignitor capability).