to make a stream sprite you need to make a .WAD file. Use the program "Wally" and make a texture called "SCROLLLAVA". This texture should look like lava. Ok now make a block and move it to entity. Make its entity func_conveyor and enable the non-solid flag. Now give it a name and give it the texture of "SCROLLLAVA". Also a texture WONT scroll if the texture name doesnt have "SCROLL" at the beginning