A: Most such videos are fake or outdated. They often show decompiling very old, simple EX4 files (pre-build 600). For modern EX4 files, they do not work.
Modern open-source projects like the Ex4-to-Multiple-Readable-Language-Converter on GitHub attempt to generate "pseudocode." This won't give you a runnable MQ4 file, but it can provide logic insights in JSON or Python formats. how to convert ex4 file to mql4
Files compiled with MT4 Build 509 or earlier (typically from 2013 or before) can often be decompiled using older software like EX4 to MQ4 Decompiler 4.0 Modern Files (Build 600+): A: Most such videos are fake or outdated