Aligning out-of-sync subtitles
At the top of your file you put all of your imports in one line, but from PEP8:


  Imports should usually be on separate lines

You define offset, but the next line you define it again.  That makes the first definition completely useless.
timeChangeSRT() should not be splitting up a string to get the right minutes, seconds, and milliseconds.  Those should be passed as arguments.
Those backslashes at the end of the lines are useless.  The indentation tells the reader, and the unclosed parentheses tells the interpreter.
You have two lines that are used both in the if and in the else blocks (the definition of newline and writing it to new).  That is a sign that they should be outside of the blocks and executed just afterwards.
Instead of using newline = '0' + str(start)[:11] + " --&gt; " + '0'..., use a format string: newline = '0{} --&gt; 0{}\n'.format(str(start)[:11], str(end)[:11])
You use old-style string formatting, but from the docs on .format() from Python2:


  This method of string formatting is the new standard in Python 3, and should be preferred to the % formatting described in String Formatting Operations in new code.



Your second function pretty much needs the same modifications as the first.  Your second function, in fact, is so similar to the first that I am sure you could define some helper functions to do some of the work so as to reduce the duplicate code.