Had to continue as a comment as lost add box with longer answer (using phone)
I had a look at a random example from the Lancs OPC .This was St James Accrington Baptisms 1862-1872.The LDS film no was 1278944. I went to the Family search Catalogue https://www.familysearch.org/catalog/search
and searched by this number. It was correct and clicking onto the link in the search result took me to full details of the original film.https://www.familysearch.org/search/catalog/623196?availability=Family%20History%20Library
In this example the register was online .( and looks as if many or even all of these Lancs registers are on the site) I was able to search for an entry and see the image for myself with the added advantage of full citation ready to paste into a profile.
England, Lancashire, Parish Registers 1538-1910," database, FamilySearch (https://familysearch.org/ark:/61903/1:1:QJD8-JDB4
: 13 October 2017), Francis Dewhurst, 27 Oct 1861; citing Christening, St James' Church, Accrington, Lancashire, England, volume , Lancashire Record Office, Preston; FHL microfilm 1,278,944.