Question: Listen From 00:56
[![enter image description here](https://i.stack.imgur.com/X68RF.jpg)](https://i.stack.imgur.com/X68RF.jpg)

The [E] part is in C Major key

and I can't understand the C#m7-5 chord at bar 3

what is this chord ? 

Where did it come from? and what is its function ?

Answer: 
Depends on the Time Signature.
==============================

The first grouping would be ideal in Time Signature with minim beats, the beats are upheld but the subdivision of the beat aids in the reading of notes.

The second grouping is correct when you have crotchet beats because there is a grouping rule that says you subdivide the beats when you have semi-quavers in Time Signatures with crotchet or dotted crotchet beats.
I would read them both the same way. This is just differences in publishing style. My guess is that the first one is an older style.