[Koby Goldberg] “Is it like a Video Editor for MPEG files”
Yes
[Koby Goldberg] “that combines and cuts parts of it without recompression”
Usually if straight cuts, or drop-ins for the same material its mostly without recompression except to mend the cut GOPs
AVCHD should be used with a intermediate codec like cineform, neoscene, the compression is so high it can choke most systems when codeding/decoding, the loss with transcoding to a intermediate codec is minimized by going by going to a higher bit count and quantization.