@Edward-Hayes said:
Sorry should have added … with notepad++
You have missed @andrecool-68’s succinct point: per the description linked, a .bsf file is:
High-definition video format used to store Blu-ray video data; encoded with Advanced Video Coding (AVC) and uses H.264 video compression; may be found on a Blu-ray video disc.
High definition video formats are binary files. Notepad++ is a text editor.
If you are having trouble understanding why binary ≠ text, and why it is unreasonable to expect a text editor to be able to read-as-text any binary format, please see this FAQ (which uses .docx as the example binary format, but is still relevant to the concepts involved). Actually, it goes beyond that FAQ, because at least in the FAQ’s example, .docx and .pdf are formats generally or often considered to contain textual information; expecting to be able to edit a textual representation of a binary compressed video format seems odd.
If your .bsf file is not the Blu-ray video format described above, you will have to tell us what kind of file “.bsf” is in your case, and why you think a text editor is appropriate for editing it.