I don't know why but I finished the Dawnguard questline and killed Harkon, did the companion quest until they needed to meet you at the Underforge BUT the regular way to becoming Hybrid doesn't work. Here's how I did it. I turned into a regular vampire via Sanguinare Vampiris first. Went to full hunger as vampire. After that, asked Serana to turn me into a Vampire Lord. I went to the underforge and perfectly timed pressing the button to drink the werewold blood and the VL transformation. Boom. I end up outside the underforge as a werewolf and then the Vampire Lord form bursts out of me. I quickly go back to revert form but instead of turning into my human form, I revert back into a werewolf. I black out and Aela speaks to me about killing some Siler hand people but I'm no longer a hybrid but just a pure werewolf. I don't know why because this is how all those Youtube videos do it. I tried loading older saves and then doing it again but it doesn't work. I turn back into a werewolf instead of a human when I revert form from VL. But I did it before this way and it only seems to work on that save file but I don't want to use that because I'm far into the game now to load to such an old file.

Here's another thing, I tried to fix the glitch by putting in the console command "player.setrace nordracevampire/nord" after I revert form from my VL (and just right before I turn into a werewolf again) so that Serana could bite me again. But this didn't work because from then on out, after I blacked out, I was in human form BUT each time I transform into a VL and revert form, I always turn back into a Werewolf, never being able to become human form again. And even in werewolf form when I press the powers button to roar, it transforms me into a VL instead of roaring. I can use my VL powers in vampire form except using revert form would turn m back into werewolf. Basically, I can alternate from VL to Werewolf and vise versa indefinitely but never back to human form unless I waited out the werewolf transformation to wear off... and even then sometimes it glitches that the werewolf form never wears off and I end up alternating from VL to werewolf but NEVER being able to turn human form ever. So this setrace solution didn't work at all.

I tried another thing, I loaded another save, I got Sanguinare Vampiris, waited the right time and went to the underforge... I drank the beast blood perfectly just in time when my screen turned red and said that my blood boils and I'm not a vampire. Surely enough, I come out of the underforge as a werewolf and blacked out and woke up with Aela as a regular Vampire-Werewolf hybrid. BUT being a regular vampire, I have no vampire lord form and I want to take it a step further. I went to the Volkihar balcony where the Soul Cairn portal was and asked Serana to turn me into a VL since the game doesn't recognize me as a vampire still. Just before she bites me and says "I promise I'll try to make this as painless as possible. Hold Still" I press my power buttons and turn into a werewolf. She still continues to bite me and it says "Vampire Lord added" BUT from being a werewolf I revert into a human form vampire immediately. Checking my Powers and Active effects tabs, I have no Beast form skill or the werewolf Resist disease active. This method completely flushed out my werewolf powers so this doesn't work either.

All these different methods to turn into a hybrid VL-werewolf like all the Youtube video says but none of it works and I don't know why this is going on because I never patched after the 1.9 patch. What's going on guys? And no I'm am not using any mods. This is vanilla Skyrim 1.9 with Dawnguard and Dragonborn and Heartfire installed.

You're not supposed to be able to be a hybrid, it is either one or the other. Being both a vampire and a werewolf at the same time is (or was) a bug in the game, not a feature. Using console commands to attempt to do this is likely to mess up your game save. Besides, I think Dawnguard may have fixed that problem.

But there are lots of Youtube tutorials that are using vanilla Skyrim dawnguard that are able to do it just fine. But somehow I glitch when I revert form from that method in VL form and instead turn back into a werewolf instead of being able to turn into human form and then asking Serana to bite me again. It's supposed to work.

Actually, it isn't supposed to work, it's not a feature in the game. Like I said, I'm pretty sure having Dawnguard installed keeps this from happening. Besides, this forum is for technical issues in the game, not for help enabling something that isn't supposed to be in the game in the first place.