i recorded a video on my phone
its my first time working in this program
when i try to open it ( to add lightin gg effects ) it wont. i tried to convert it ( mp4 and mov wont open at all, only .avi does and when it does and i try to play the video it says it couldnt find h264 decompressor or something like that).
any help at all ?
AVI and MOV are just containers for video codecs. What codec is inside of it can make a big difference to how well it works for various things. When you converted it to an AVI, it seems you still left it in the h.264 codec. CS4 didn't work well with h.264 video. Try converting it to something else, like the Cineform codec (free from GoPro) or a Quicktime with the PNG codec.
You may have to transcode the file before you can use it in AE. CS4 did not have the same decoding capabilities as CS6 or CC because the codecs were not in use then.