Ice water may not be cold enough to keep the ether in 100% liquid state. If it is vaporizing/boiling at even the smallest amount, it will create pressure in the tube/bulb/bourdon tube and purge out of the liquid solder. Try dry ice for a colder bulb.
In the videos it shows ice water with rock salt. Another fellow just has the bulb in the freezer while doing the soldering. So may the freezer is better but yes, dry ice might be the perfect solution.
