"Shin-etsu" is the lube recommended for the window channels by the service manual. It's available at the dealer but a little pricey. It can be applied with a Q-tip after cleaning the channel. A little goes a long way.
This is really normal maintence for the Insight and will prevent the window rubber from bunching up and destroying itself.
It works great on the door, hood and hatch gaskets also
My former '04 Insight CVT had it's drivers window smashed after somone locked the keys in the car, then tried unsuccessfully to use a "slim jim" to work the latch mechanism and ruined the lower outside window trim piece. Whoever installed the factory replacement glass butchered the job, and, as a result, the window was binding heavily. I was quite happy (and astonished) when my local dealer replaced the entire window channel system and the butchered trim piece under warranty. All the more amazing since they didn't sell the car either new or used. It paid off for them a few weeks ago when I traded the Insight in on a new HCH II.
FWIW, window binding is one of the few a common concerns on Insights.