The following is a stackoverflow.com link that might be useful showing
how to extract a substring from inside a string in Python?
Unfortunately, MySQL regexp simply returns true if the string exists.  I have found substring_index useful if you know the text surrounding the target...
select case when ColumnName like 'hotel____' then substring_index(ColumnName,'hotel',-1)
            when ColumnName like '/____.html' then substring_index(substring_index(ColumnName,'/',-1),'.html',1)
            else ColumnName
             end digit_extraction
  from TableName
 where ...;
The case statement above isn't necessary because of the way substring_index works (by returning the entire string if the search string isn't found).
select substring_index(substring_index(substring_index(ColumnName,'hotel',-1),'/',-1),'.html',1)
  from TableName
 where ...;