I have seen a blood knot used several times by mates for a quick fix when using mono. I have used it to join mainline to slightly heavier leader when I use to KM fish, never had one fail. If it was me I would just re-spool the reel and be done with it.
If it was me I would pull the line off and put the extra line on as backing and use a plat to no name knot. I would then cover it with aquaseal to make it nice and smoooooooth
Steve
BTW thanks for the video. Thats why I like this site. Always learn something new.