This FM8 Wavetable is a custom Wavetable picked from the user folder within Serum Wavetables folder, therefore you won't get it in your own instance of Serum. This custom FM8 Wavetable is also not included in the provided HTU_Serum_Resources.zip resource file available for download.
In fact, in the Dubstep video you're watching, @7skies mentioned something like " let's use that one we created before ... " and you have to refer to the VideoTutorial 04 - Wavetables where around 20 minutes time, @7Skies is using Native Instrument FM8 synth to create this FM8 custom Wavetable inside Xfer Serum. You'll be able to do the same watching this video but you'll have to own NI FM8.
Hope that's answering your question.