In a recently uploaded video, seed bank Fast Buds has shown how they harvest their cannabis seeds. In the breeding facility, they first select the first plants that are ready to harvest. For the purpose of the video, they select a Purple Lemonade auto plant. As they chop the plant off the block, they hang it head down in their drying room.
After that, it's time to get the buds off the branches, and get those seeds out. The process is quite interesting to watch, so have a look at the video below to see how they do this.