Link doesn't work for me either. How long have you had the shrimp? I purchased some shrimp at what I though was a good deal, it was as I got some hitchhikers like the seed shrimp, hydra and planaria. Fenben (Fenbendazole) got rid of the planaria and some hydra. I got mine from Petsmart-its a dog dewormer. If you have an agriculture store (Farm and Fleet/Tractor Supply) you can find it as a goat dewormer as well. Jehmco also sells it, oh guess not any longer, but you can find it online.
For the seed shrimp-its a bit harder. They will out compete the shrimp and eventually the only shrimp will be the seed shrimp. What I did was buy the glass planaria traps and on a nightly basis for about a month I wild put a small amount of the smelliest food in the trap and then empty it out the next morning. For the first week the traps were full of seed shrimp. Eventually I put a enough of a dent that my shrimp were able to out compete them. I also purchased some petri dishes to put the shrimp food in and that way I could closely monitor how fast the food was eaten.
The detritus worms are from excess waste in the substrate. Best way to clear them is going to be through a good substrate cleaning and then cutting down feedings. If you have a couple left they won't harm the shrimp. In larger numbers they can strain water parameters in smaller tanks.