Why is vacuum sealing so important? Most types of plastic resins are hygroscopic, however, humidity is absorbed by the plastics. To keep the Extrudr filament dry, every spool is vacuum sealed immediately after drying and processing. At this stage the filament is still warm.
The humidity is responsible for tiny bubbles due the extruding with your printer. To prevent these bubbles and to increase your printing quality, you could put the filament into a oven (do not try at home!) with 80 C for about 2 hours.
To storage the filament keep it on a dry place.