A scrim is a very light textile made from cotton, or sometimes flax. Their lightweight and translucence means it is often used for curtains. The fabric can also be used for bookbinding and upholstery. Scrims have also seen extensive use in theatre where they are often used for special effects. In theater a scrim can refer to any such thin screen and are made out of a wide variety of substances.
A transaxle is a complex machine that brings together a transmission and final drive components like a differential. In that way, a transaxle is capable of driving the axles without any additional components.
(Note: Transmission fluid will almost never be low. The automatic transmission / transaxle is a sealed system, requiring little maintenance. If your fluid is low, it most likely means you have a leak in the system, such as a worn seal or a crack somewhere.