Compare 2 csv files and delete rows - Shell - bash

Question

I have a 2 csv files. One has several columns, the other is just one column with domains. Simplified data of these files would be
file1.csv:
John,example.org,MyCompany,Australia
Lenny,domain.com,OtherCompany,US
Martha,site.com,ThirdCompany,US
file2.csv:
example.org
google.es
mysite.uk
The output should be
Lenny,domain.com,OtherCompany,US
Martha,site.com,ThirdCompany,US
I have tried this solution
grep -v -f file2.csv file1.csv >output-file
Found here
http://www.unix.com/shell-programming-and-scripting/177207-removing-duplicate-records-comparing-2-csv-files.html
But since there is no explanation whatsoever about how the script works, and I suck at shell, I cannot tweak it to make it work for me
A solution for this would be highly appreciated, a solution with some explanation would be awesome! :)
EDIT:
I have tried the line that was suppose to work, but for some reason it does not. Here the output from my terminal. What's wrong with this?
Desktop $ cat file1.csv ; echo
John,example.org,MyCompany,Australia
Lenny ,domain.com,OtherCompany,US
Martha,mysite.com,ThirCompany,US
Desktop $ cat file2.csv ; echo
example.org
google.es
mysite.uk
Desktop $ grep -v -f file2.csv file1.csv
John,example.org,MyCompany,Australia
Lenny ,domain.com,OtherCompany,US
Martha,mysite.com,ThirCompany,US
Why grep doesn't remove the line
John,example.org,MyCompany,Australia

Answer 1

The line you posted, works just fine.
$ grep -v -f file2.csv file1.csv
Lenny,domain.com,OtherCompany,US
Martha,site.com,ThirdCompany,US
And here's an explanation. grep will search for a given pattern in a given file and print all lines that match. The simplest example of usage is:
$ grep John file1.csv
John,example.org,MyCompany,Australia
Here we used a simple pattern that matches each character, but you can also use regular expressions (basic, extended, and even perl-compatible ones).
To invert the logic, and print only the lines that do not match, we use the -v switch, like this:
$ grep -v John file1.csv
Lenny,domain.com,OtherCompany,US
Martha,site.com,ThirdCompany,US
To specify more than one pattern, you can use the option -e pattern multiple times, like this:
$ grep -v -e John -e Lenny file1.csv
Martha,site.com,ThirdCompany,US
However, if there is a larger number of patterns to check for, we might use the -f file option that will read all patterns from a file specified.
So, when we combine all of those; reading patterns from a file with -f and inverting the matching logic with -v, we get the line you need.

Answer 2

One in awk:
$ awk -F, 'NR==FNR{a[$1];next}($2 in a==0)' file2 file1
Lenny,domain.com,OtherCompany,US
Martha,site.com,ThirdCompany,US
Explained:
$ awk -F, ' # using awk, comma-separated records
NR==FNR { # process the first file, file2
a[$1] # hash the domain to a
next # proceed to next record
}
($2 in a==0) # process file1, if domain in $2 not in a, print the record
' file2 file1 # file order is important